First, pull up the invitation page and look closely at the rules printed beside the application window. A surprising number of users ignore these notes and then complain about getting rejected.
The next practical step is filtering your backlog down to about half a dozen polished examples. A single unfinished mock-up in your set can undo the effect of five good ones.
Another typical mistake is cramming logos, illustrations, and interfaces into one view without a clear focus. Make the top of your page immediately clear, so visitors can tell what you do without scrolling.
A useful summary of the submission guidelines is collected in https://dribbble.com/.
Right before you send the application, open each upload on a different device and compare the colors and edges. Fix small details like uneven spacing, orphaned letters, and watermarked mock-up photos before anyone sees them. These are the exact details that make a profile feel either professional or rushed to a first-time visitor.
