Your App Store screenshots do more selling than your description ever will. Most visitors decide from the gallery alone, in the second or two before they scroll past. A strong set can lift your install rate more than any single feature you could ship that week.
These are the mistakes we see most often when we review a gallery, and the quick fixes that move the needle.
1. Leading with your least clear screen
The first shot carries the most weight and gets the least patience. If it needs a caption to explain what the app is, it is already too slow. Lead with the one screen that shows your core value at a glance, and save the nuance for later frames.
2. Captions no one can read at thumbnail size
Search results show your screenshots small. A caption that reads fine on your monitor turns to mush at thumbnail size. Keep captions to a few strong words, set them large, and give them real contrast against the background.
3. Frames that are not the size Apple wants
App Store Connect is unforgiving about dimensions. A gallery that looks great in your design tool gets rejected because a frame is a few pixels off. Design at the exact device sizes Apple expects so upload is never a guessing game.
4. One gallery for every market
Shipping English screenshots to every store leaves conversions on the table in markets that would happily install a localized app. You do not need a separate design per language, just the same design rendered per locale with the copy translated.
5. Ignoring the first-three rule
On most devices only the first two or three screenshots are visible without scrolling, and the majority of visitors never scroll. Treat those three as the whole pitch: problem, product, proof. Everything after is a bonus for the people already interested.
A gallery is not a feature list. It is the shortest possible argument for why this app is worth a tap.ScreenMocks design notes
6. Decoration instead of hierarchy
Gradients, stickers, and confetti do not make a screenshot convert. Clear hierarchy does. Let type weight and spacing carry the message, use one accent color with intent, and keep the device the hero of the frame.
7. Never testing a second version
The first gallery you ship is a hypothesis, not a conclusion. The teams that climb the charts try a second order of screens, a sharper lead caption, or a different hero, then keep whichever wins. Make a variant cheap to produce and you will actually run the test.
Fix all seven in an afternoon. Start from a template, drop in your screens, and export every size and language in one pass.