It's fun to experiment with colors! Double dip from yellow into blue to make shades of teal and green, or from yellow to red for coral tones. Mixing Green and Red will yield a darker color.
You can use anything in your pantry that creates color. Take a look at your tea collection to add interesting color to the eggs. You may have to soak, dry and soak again in other colors to achieve your desired effect.
To add patterns to your eggs, try decorating the eggs with beeswax in a polka dot pattern or stripe, or whatever you fancy. Try wrapping pieces of twine or rubber bands around them before soaking.