Using AI to Make Posters Without Losing Your Brand

The good news is it's fixable, and it doesn't take a designer. It takes about twenty minutes to write down what your brand actually is, in a form the AI can follow, and then you reuse that forever. Here's exactly how I do it, with the real prompts I use.

Most instructors' first instinct is to paste their hex codes into the prompt. Good instinct, but it doesn't work on its own. I did it for months and the posts still looked AI-made, just in navy instead of purple.

That's because the tells aren't in the palette. They're in the composition and the surface. Once you know them you can't unsee them:

• The coloured strip down the left edge — a vertical accent bar that no human designer asked for.
• The brush stroke — a painterly swoosh behind or under the headline, usually in an accent colour.
• Fake depth — a gradient in the background, a soft glow behind the text, a drop shadow on everything.
• Everything centred — headline centred, subhead centred, details centred, generous symmetrical margins. Safe and forgettable.
• Decorative filler — little sparkles, dots, corner flourishes, abstract shapes drifting in the background.
• Stock-perfect people — a glossy, evenly-lit woman mid-stretch who has never been to your hall in Dunmanway.
• Letters that are nearly right — the headline reads fine at a glance and falls apart when you look twice.

Put your colours on top of that and you get an AI poster in your colours. The brand isn't the palette. It's the layout, the type, the flatness or the texture, the amount of empty space, and — just as importantly — the things you never do.

AI can't look at your Instagram and absorb the vibe. It needs instructions. So write your brand down as a short spec — one screen of text, no more — that you paste at the top of every prompt.

Four things make it work:

• Colours with jobs. Not "my colours are navy and blue" but "the background is always #1E293B, the type is always white". Give each colour a role or the AI will swap them around.
• Type with weight, case and alignment. Font name alone isn't enough — say bold, say all-caps or sentence case, say left-aligned.
• A layout rule. Where the headline sits, where the details sit, how much of the square the headline should fill.
• A ban list. This is the part everyone skips and it's the part that does the work. Name the AI habits from the last section and forbid them explicitly.

Here's a blank you can fill in for yourself:

BRAND: [your studio name]

Colours (with jobs):
- Background: [hex]
- Headline type: [hex]
- Accent, used sparingly for [what]: [hex]

Type:
- Headline: [font], [weight], [ALL CAPS / Sentence case], [alignment]
- Details: [font], [weight], [alignment]

Layout:
- Format: [square 1:1 / portrait 4:5]
- Headline sits [where] and fills about [x]% of the square
- Class details sit [where], small
- Wordmark [where]

Tone: [three adjectives]

Never use:
- [your ban list]

Mine is deliberately strict. My posts are big flat blocks of colour with white writing across them — that's it. No photos, no shapes, no texture. It's not sophisticated, but it's mine: people in Clonakilty know a Core Studio post before they read a word of it.

BRAND: core studio — Pilates & DanceFit, West Cork

Colours (with jobs):
- Background: solid #1E293B (deep navy) OR solid #38BDF8 (sky blue).
  One flat colour, edge to edge. Never both in the same poster.
- Headline type: #F1F5F9 (off-white). Always.
- No third colour.

Type:
- Headline: DM Serif Display, ALL CAPS, left-aligned
- Details: DM Sans, regular, left-aligned, small
- Wordmark "core studio" always lowercase

Layout:
- Square 1:1
- Headline in the upper-left, three or four words max,
  filling about 60% of the square
- Class details in a single small block in the bottom-left
- Wordmark bottom-right, small
- Wide, uneven margins — more space at the bottom than the top

Tone: warm, direct, unfussy

Never use:
- gradients, glows, drop shadows or any faux 3D
- brush strokes, swooshes, splatters or painterly effects
- a vertical coloured bar down any edge
- sparkles, dots, corner flourishes or abstract background shapes
- photographs or illustrations of people
- centred text
- more than one colour behind the type

Write yours once and keep it somewhere you can grab it in two seconds. Better still, paste it into a Claude Project or a ChatGPT custom instruction so it's applied every time without you thinking about it.

This is the prompt I used to write, and it's the one that produces the poster everyone else has:

Make me an Instagram post for my new DanceFit class
starting in September.

What comes back is competent and completely anonymous. Purple-to-orange gradient. "DANCEFIT" in a glowing rounded sans-serif, centred. A brush stroke underneath it. A silhouette of a woman mid-jump. Two sparkles. Nothing in it says West Cork, or me, or the actual class. It would work equally well for a gym in Manchester, which is exactly the problem.

Same tool, same thirty seconds, completely different result. The structure is: brand sheet, then the copy for this specific poster, then the ban list restated at the end because that's where it sticks.

Design a square Instagram poster for my class. Follow this
brand sheet exactly — it is not a suggestion.

[paste your brand sheet here]

This poster:
- Background: solid #38BDF8
- Headline: DANCEFIT IS BACK
- Details block, exactly this text on four lines:
  Thursdays 7.15pm
  Cox's Hall, Dunmanway
  6 week term from 17th September
  €48 for the term
- Wordmark: core studio

Flat colour only. No gradient, no shadow, no glow, no brush
stroke, no shapes, no people, no sparkles, nothing centred.
If you are tempted to add a decorative element, leave it out.

That last line does more than it looks like it should. AI wants to fill space — it treats empty space as an unfinished job. Telling it in plain words that the emptiness is the point is what gets you a poster with confidence in it.

The first attempt is rarely right. Don't re-roll the whole thing hoping for luck — say what's wrong in one short sentence and ask for that one change. These are the follow-ups I use constantly:

• "Flatten it. Remove every gradient, shadow and glow — one solid colour edge to edge."
• "The headline is too small. It should fill about 60% of the square."
• "Delete the decorative shapes in the background. Leave that space empty."
• "Left-align everything. Nothing centred."
• "The venue name is misspelled — it's Cox's Hall. Regenerate with the text exactly as written."
• "Keep this composition exactly, change the background to #1E293B."

That last one is how you get a set. Once you've got one poster you're happy with, ask for the same layout with different copy and the other background colour, and suddenly your feed looks planned instead of assembled week by week.

Before you post anything, cover the wordmark with your thumb and look at it for five seconds, the way someone scrolling actually would. Then ask: would one of my regulars know this was me?

If the answer is no, the poster isn't finished — and it doesn't matter how nice it looks. A beautiful post nobody attributes to you is an advert for AI, not for your Thursday class. It's a blunt test and I fail it more often than I'd like, but it's saved me from posting a lot of very polished nothing.

One more thing that has quietly saved me a lot of hassle. Half the effort in a poster prompt is the boring half — the day, the time, the venue, the term dates, the price, whether there are spaces left. I used to type those from memory and I got them wrong often enough to be embarrassing.

StudioFlow connects directly to Claude and ChatGPT through MCP, so the assistant can read my actual schedule. I say "make me a poster for Thursday's DanceFit in Dunmanway, using my brand sheet" and it pulls the time, the venue, the term start and the number of spaces left straight out of my classes. No copy-paste, and no poster advertising a class that filled up last week.

The AI does the part I'm bad at. The brand sheet keeps it sounding like me. That's the whole trick — your brand still has to exist before you can hand it over.