Take a moment to study the sign-up requirements and the short description of what reviewers expect from every candidate. Many people skip that step and later wonder why their application was declined.

When you know what kind of work gets featured, hand-pick a few samples instead of uploading everything you have. A single unfinished mock-up in your set can undo the effect of five good ones.

People often damage their own chances by showing too many disconnected directions at once. Keep the cover section orderly and let the viewer understand your specialty within the first seconds.

A useful summary of the submission guidelines is collected in https://dribbble.com/.

Test all your preview files on at least two displays, because cropping and brightness often look wrong after upload. Watch out for stock photo watermarks, placeholder labels, and missing glyphs in your interface shots. Reviewers notice these tiny flaws immediately, even if the overall concept is strong.