This article pointed out that a red button amidst a green palette converted better in one instance, because the red button contrasted starkly. That's also my cu

This article pointed out that a red button amidst a green palette converted better in one instance, because the red button contrasted starkly. That's also my current theory on how to make an app icon. For my App Store apps, I choose loud colors that contrast well with other apps in the category. I look at how the icon stands out in searches on iPhone, iPad, and iTunes. I still want a beautiful icon, but my primary concern is whether it pops. Unfortunately, it's hard to test the theory.