Post rules
Social Media Post Rules: The 12 Checks to Run Before You Post
Twelve rules for a social post and seven for prompting the tool that drafts it. Every one of them is written so that one person can check it by eye, in seconds, on a phone, without opening an analytics tab. Run them over your last 10 posts before you write the eleventh.
Key takeaways
- The first line decides everything downstream, because the feed hides the rest of the caption behind "more" until someone taps.
- One idea and one ask per post. Two asks split the click, and three teach the reader to ignore all three.
- Ten posts with ten different ideas have tested nothing. The same idea in five formats is a test.
- AI content reads as AI when the prompt carried adjectives instead of facts. The tool is rarely the problem.
- The rules are free and correct, and following them on 30 posts a month is a job rather than a decision.
The constraint
What a Stranger Actually Reads
Every feed truncates the caption and hides the rest behind more. So the post you published and the post a stranger reads are two different pieces of writing, and only one of them decides whether the other gets opened.
What you wrote
We are so excited to finally share this with you all. Our team has been working on it for months and we could not be prouder of how it turned out.
It sold out in nine days last time, so we made twice as many.
Third party tested, 30g of protein, and 1,400 reviews at 4.6.
What a stranger reads
We are so excited to finally share this with you all. Our team has been working on it for months and ... more
The other two paragraphs, including the only sentence in the caption a stranger had any reason to stop for, sit behind that one word.
Rules 1 to 9
What You Settle in the Caption
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1
The first line has to earn the second
Every feed cuts a caption after a line or two and hides the rest behind "more". So the first line is not the introduction, it is the whole pitch. Check: read the first line only. Would you tap? "We are excited to announce our summer collection" fails. "Three people returned this last month, so we changed it" passes.
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2
The first three words carry the hook
Not the first sentence, the first three words, because that is how far someone reads before deciding. Check: cover the caption except for the first three words. If nothing survives, the hook is buried in the middle where nobody will find it.
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3
One idea per post
A post that covers the sale, the new flavour and the founder holiday covers nothing, because the reader has to pick which part matters and most will not bother. Socialinsider read 9,117,401 posts from 82,952 business pages and found captions under 30 words take the higher engagement rate, which is usually one idea told once. Check: say the post out loud in one sentence. If you need the word "and", cut something.
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4
One call to action, at the end
Two asks split the click and three train people to ignore all of them. Check: count the asks. Save this, follow us, shop the link and DM us for a code is four posts fighting each other.
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5
Write it for a stranger
Back in stock, as promised, and you asked for it all assume a relationship the reader does not have. Check: hand the caption to someone who has never heard of the brand. If they cannot say what is being sold, the post is written for existing customers only.
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6
Give one reason to believe
A number, a sentence from a real review, a named ingredient, a source. Check: find the line a sceptic would accept. If there is not one, the post is a claim and it is competing with every other claim in the feed.
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7
Say it, do not tease it
Link in bio is not a call to action, it is a direction. Check: does the post say what happens after the tap? A reader who does not know what is on the other side does not tap, and curiosity alone runs out fast.
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8
Drop the hashtags, or at least stop repeating them
Metricool measured 24,364,803 posts across 375,118 accounts and found that posts carrying at least one hashtag took 31.70% fewer views and 33.89% fewer interactions than the platform average. Identical tags on every post are worse again, because they describe the account rather than the post. Check: put the last 10 captions side by side. If the tags are the same on all 10, pick them per post or drop them.
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9
Post one idea in five formats, not five ideas once each
An idea that works is found by repeating it, because one post is never enough to tell whether the idea failed or the execution did. Check: look at the last 10 posts. If there are 10 different ideas and no repeats, nothing has been tested yet.
Rules 10 to 12
What You Settle Before a Word Is Written
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10
The image has to work at thumbnail size
People meet the image at the size of a fingernail, not at the size it looks in your editor. Check: shrink it on your phone until it is the size of a stamp. If the words disappear, the post has no words.
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11
Show the product being used, not floating
A bottle on white says what it looks like. A bottle in a hand on a kitchen counter says who it is for and when they reach for it. The second one is the post. The first one is a catalogue photo that wandered into a feed. Check: count how many of the last 10 posts show the product in a hand, on a table, or in the room it is used in. Zero means the feed is a catalogue.
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12
Put a person in the frame
A face stops a scroll, and a post with no person is competing against a feed of posts that have one. This is the cheapest fix on the list, because it does not need a studio, only a hand, a shoulder or a half a face. Check: count how many of the last 10 posts have a person, or any part of one, in the frame. If the count is zero, this is the first thing to change.
Where the two numbers come from
Rule 3 cites Socialinsider, which read 9,117,401 posts from 82,952 business pages and found captions under 30 words take the higher engagement rate. Rule 8 cites Metricool, which read 24,364,803 posts from 375,118 accounts to February 2026 and found that posts carrying at least one hashtag took 31.70% fewer views than the platform average. The same study found brands publishing 24.04% more than the year before, with views up 26.56%, which is the volume the twelve rules have to survive.
Check yourself
Three Ways to Run the Twelve on Your Own Account
Everything below runs in your browser. Nothing is uploaded, nothing is stored, and no account is needed. Between them they cover ten of the twelve: one caption at a time, ten posts at a time, and the image. The last two are rules 11 and 12, whether the product is being used and whether anybody is in the frame, and no tool can see either. Open your own photograph and answer those yourself.
Tool 1 of 3
Check One Caption: Rules 1 to 8
Paste a caption and it is checked against eight of the twelve rules below, the eight a machine can read without seeing the image. It runs in your browser, so nothing is sent anywhere and nothing is stored. Load the example first if you want to see what a failing caption looks like.
Example: the caption in the box on the left
Rules passed
How it arrives in the feed
yourbrand
... more
Everything below that cut is read by the people the two visible lines already convinced.
Tool 2 of 3
Check Ten Posts: Rules 1, 4, 8 and 9
Open your account, look at the last 10 posts, and count four things. Put them here and this does the rest: which rules your grid already holds, which one to fix first, and what following all twelve costs at the volume you actually publish.
Four questions about your last 10 posts, and one about the month. It runs in your browser and nothing is sent anywhere.
Out of your last 10 posts.
Example: the numbers in the boxes on the left
Rules your grid holds
What fixing it costs per month
Tool 3 of 3
Check the Image: Rule 10
The feed and the profile grid crop to different shapes, so the post you made and the post a stranger finds on your profile are not the same picture. Pick an image and both crops are drawn, with what each one cut. It is never uploaded. Rules 11 and 12 are not here, because a tool that asked whether the product is in use and then agreed with your answer would be checking nothing.
It stays on your device. Nothing is uploaded, nothing is stored, and the page has no way to send it anywhere.
Rule 10, on the two surfaces that crop it
Pick an image on the left. The feed carries your shape, between 1.91:1 and 3:4. The profile grid crops everything to 3:4, so a square or landscape post loses its edges there whatever it looked like when you made it.
Rule 10. Readable where it is cropped
Read the grid crop. Anything that has to be read and sits in the strip the grid took is gone for everybody who meets you on your profile, and no caption puts it back.
Before and after
The Four Rules That Fail Most, Written Both Ways
Same product, same offer, same week. The left column is how the line usually arrives, the right column is the same line after one rule is applied. Nothing here needs a designer or a budget.
| The rule | How it usually arrives | The same thing, fixed |
|---|---|---|
| The first line earns the second | We are excited to announce that our best seller is finally back in stock. | It sold out in nine days. We made twice as many this time. |
| One ask, at the end | Link in bio. Comment below. Save this for later. Follow for more. | Link in bio for the restock list. We email it before it goes public. |
| One reason to believe | Premium quality ingredients, made with care, loved by our community. | Third party tested, 30g of protein, and 1,400 reviews at 4.6. |
| Written to the reader | Our team has worked incredibly hard on this and we could not be prouder. | If the last one gave you an afternoon slump, this is the fix. |
The right column is not cleverer writing. It is the same information with the brand taken out of the subject position and one number put in.
Prompting
Seven Lines That Change What Comes Back
These do more for the output than switching tools does, and all seven are about the input. A model given nothing specific returns the most average version of what it has read, and average is what the feed is already full of. Left is what people type. Right is the same instruction with something in it the model could not have guessed.
| The rule | What gets typed | What to type instead |
|---|---|---|
| Facts, not adjectives | Write a post about our premium, all natural protein powder. | 30g protein, 12 servings, one ingredient, made in Utah. Write a post about it. |
| A real review, not a persona | The audience is health conscious women aged 25 to 40. | A customer wrote: "I stopped needing the 3pm coffee." Write to whoever says that. |
| Platform and format first | Write me a post about the new flavour. | Instagram carousel, six frames, one line per frame. Topic: the new flavour. |
| Ask for ten, keep one | Write the caption. | Ten openings, no explanation, no preamble. I will pick one. |
| A structure, not a blank page | Make it sound like our brand. | Here is a post that worked. Same structure, my facts. Do not reuse the words. |
| Tell it what to avoid | Make it engaging. | My last three posts opened with these lines. Do not write a fourth like them. |
| Never ship the first draft | Copy, paste, publish. | Cut the opening sentence, then read it aloud. What you would not say, delete. |
The middle column is not a bad prompt because it is short. It is a bad prompt because everything in it is true of every competitor as well.
What a month of the rules costs
The rules are free. Following them is the job.
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Deciding what to post
YouThirty decisions a month, made the morning the slot arrives.
SelzeeResearched from what is already running in your market, by models already holding your product, your reviews and your voice.
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Applying the 12 rules
You360 checks a month, the first thing dropped when the week gets short.
SelzeeHeld in the templates and applied before you see a draft.
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Making the image
YouA shoot, an editor, or a template you used twice this month.
SelzeeFinished visuals built to survive the grid crop, sized for every channel.
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Testing one idea
YouRule 9 wants the same idea in several formats. Volume kills it first.
SelzeeVariations made together, so the test exists rather than being intended.
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Twelve rules, thirty posts
360 checks
All twelve applied before you see them. No brief, no call.
Social Media Post Rules: FAQ
01 How often should I post on social media? +
Often enough that one post does not have to carry the month, and consistently enough that the account is not judged on its worst week. The number matters less than what the rules on this page do to each post, because posting more of something that breaks rule one just produces more posts nobody reads. If you are choosing between five careful posts and twenty rushed ones, the honest answer is that twenty careful ones beat both, and that is a production problem rather than a strategy problem.
02 Do hashtags still work? +
They work as a description of the individual post and not as a signature on the account. The failure we see most is the same three tags on every post for a year, which tells the platform the same thing every time and matches nothing anyone is searching for. Pick them per post from what is actually in the post, or leave them out and put the effort into the first line instead.
03 How long should a caption be? +
Long enough to say one thing completely. Length is not the rule, structure is: the first line has to earn the second, there is one idea, and there is one ask at the end. A four line caption that follows those beats a forty line caption that buries the point in paragraph three, and a forty line caption that follows them is fine too.
04 Does AI content perform worse? +
Nothing ranks a post down for being made with a tool. What performs worse is generic content, and generic is what a model produces when it is given adjectives instead of facts, a persona instead of a real customer sentence, and no instruction about what to avoid. The seven prompt rules on this page exist because the tool is not the problem, the input is.
05 What makes AI content look like AI? +
Three things, and all of them come from the prompt. The opening announces what the post is about instead of starting inside it. The claims are adjectives with nothing behind them. And the phrasing is the most common phrasing, because the model was never told what had already been used. Fix the input and the output stops being recognisable.
06 How do I know whether a post worked? +
Decide before you post what would count, then look once. If the idea is being tested, the thing to watch is whether people stopped, not whether they liked it, and that means saves, shares and profile visits rather than the number under the heart. One post cannot tell you whether the idea failed or the execution did, which is why rule nine asks for the same idea in five formats.
Keep exploring: AI social media post generator, Instagram caption generator, content idea generator, AI content creation tools.