Designing watch faces for a tiny screen on your wrist is a game of constraints. Become familiar with these constraints and use them to make your faces more beautiful and useful.
Use a grid
A grid will introduce a systematic and uniform layout to your design.
Use multiple colors
Wearers love to customize their watch face so consider how your design looks using a variety of colors. This can be achieved by giving your design elements alpha values instead of solid colors.
Avoid light colored backgrounds. Black works best as it blends seamlessly into the watch hardware.
Vary hand lengths
The hour hand should be at least ⅓ shorter than the minute hand. This will make the time easier to read.
Ensure your design elements are bold enough to stand out as subtle details are easily lost in a real world context.