Begin with the outcome
The first screenshot should answer what the app helps a visitor do. Lead with the outcome, then use later screens to explain the workflow, proof points, and supporting features.
Write one message for each screen before opening a design tool. If two screens make the same point, combine them or use the space for a genuine use case.
Use a practical sequence
A useful sequence is core promise, primary action, key workflow, helpful detail, evidence or overview, and final benefit. Not every app needs six screens, but the structure prevents a random gallery of UI captures.
Each screen must make sense alone because stores may display, crop, or reorder images across devices.
Keep the visual system consistent
Use a repeated type system, restrained colors, and a consistent device frame. Backgrounds can connect the sequence but should not hide the real interface or reduce copy contrast. Use real current screens and only claims the product can support.