AI video prompts that actually work: a practical guide
What separates prompts that render clean from prompts that fall apart: specificity, physical anchors, scene constraints, and real examples.
Specificity beats adjectives
The most common prompting mistake is describing vibes instead of things. Beautiful woman in a nice kitchen gives the model almost nothing to hold onto, so it invents details freely and every render invents different ones. Prompts that render clean read like stage directions, not poetry.
Replace every adjective with a noun. Not beautiful: early thirties, light freckles across the nose, hazel eyes. Not nice kitchen: white tile backsplash, wooden countertop, morning light from a window on the left. Each concrete noun is a constraint, and constraints are what keep renders stable.
Count the nouns in your prompt before you render. Ten or more concrete visual nouns is a good prompt. Fewer than five is a wish. This single habit fixes more bad renders than any model upgrade.
Physical anchors
Anchors are the small, distinctive details the model can grip: a beauty mark, a specific piece of jewelry, a scar, a tattoo, a hair parting. They work because they are unusual enough to survive the model's tendency to average everything toward generic.
Give every character and every important object at least two anchors. For a person: three small gold hoops on the left ear only, plus a square pendant. For a product: matte black bottle, plus a white cap with a ridge pattern. When a render comes back wrong, check the anchors first. If they drifted, the prompt was paraphrased or the scene was too chaotic.
Anchors also speed up iteration. When only the anchor is wrong, you know exactly which sentence to fix, instead of rewriting the whole prompt and introducing three new problems.
Constrain the scene
Every prompt should contain one action, one camera behavior, and one setting. She picks up the bottle, the camera holds steady at waist height, morning kitchen. That is a complete scene description. Adding a second action (then she laughs and turns) or a camera move (then it swoops) is where renders fall apart.
Banish crowds, mirrors, and text from your prompts unless the scene absolutely needs them. Crowds multiply faces the model must keep consistent. Mirrors double the rendering work and usually produce a stranger. Text on labels or signs renders as gibberish more often than not.
Describe the light in one phrase: morning window light from the left, or warm overhead kitchen light. Lighting is the cheapest way to make a render look expensive, and one phrase is all it takes.
Write the line like dialogue
Spoken lines should sound like something a person would actually say, with contractions and fragments. Write it, then say it out loud. If you stumble, the lip-sync will too. Short declarative sentences render cleaner than long winding ones.
Keep lines under about twenty words for short-form video. Longer lines increase the chance of the mouth drifting out of sync halfway through, and they test viewer patience. One idea per line. If you have two ideas, that is two clips.
Match the line to the action. If she is picking up the bottle, the line should be about the bottle, not about her morning routine. Action and dialogue pointing the same direction makes the clip feel directed instead of assembled.
A prompt that works, annotated
Here is a complete prompt for a ten-second UGC clip, with why each part earns its place. Character: woman in her early thirties, light freckles across the nose, hazel eyes, dark hair parted in the middle, three small gold hoops on the left ear only. (Four anchors: freckles, eyes, parting, hoops. Nothing paraphrased from the bible.)
Action and scene: She stands in a kitchen with white tile backsplash, holding a matte black serum bottle up at chest height, morning window light from the left. Camera holds steady at waist height, single take. (One action, one camera, one setting, one light phrase. No crowds, no mirrors, no text.)
Line: Okay, this is the third serum I have tried this month, and it is the first one that did not pill under makeup. (Nineteen words, spoken like a person, matched to the bottle in her hand. Presenter mode: describes her testing process without claiming a medical result.)
What to do when it breaks
Change one variable at a time. If the face drifted, the problem is the character description: compare it word for word against the bible. If the hands look wrong, the problem is the action: simplify it to one motion. If the background melts, the problem is the scene: remove one element.
Keep a log of what you changed per render. Prompt, anchor check, scene elements, line. When a render finally lands, you want to know exactly which version worked so you can reuse it as a template for the next fifty clips.
Most bad renders are fixed in two iterations once you isolate variables. The people who burn hundreds of credits are the ones rewriting the entire prompt each time and re-rolling every problem at once.