Beautiful, compelling icons are a fundamental part of a good user experience. Far from being merely decorative, icons play an essential role in communicating with users. Focus on a unique shape; some icons have many colors or they feature gradients, but they all start with a simple shape. That allows them to be recognizable at a distance and at a glance. Icons are seen in a range of different sizes. They are large in the App store, get small on the home screen and even smaller in the notification centre and in groups. Make sure your design scales well and is clear at any size.

The designer should also test the icon on different wallpapers; while it might look great against a traditional backdrop, iOS raindrops for example, there’s no guarantee it looks great on all wallpapers. And try grouping your designs into folders to evaluate how they look.