Very good tips, usually work for me, and explained very well:
- Don’t use words on the App Icon
- Work with simple forms
- Use details
- Use vibrant colors when possible
- Don’t make promises your app does not fulfill
- Keep the visual language and art style from the app
- Test design with and without borders
- Get creative, do something your competitors didn’t
- Choose a small SpringBoard name
- Test the icon
So, to sum it up - being simple but standing out, being creative without over-promising and testing what you do over and over again.
Simple, no? Well, no. But it works. I know.