Choose colors according to your flag's design. Don't just use dark colors -- be creative and add colors according to the features of the place you are making the flag for.
Use the lightest base color first, then proceed to add the other color(s) in their areas. Once you've laid everything down, blend by running the previous (lighter) color over the...
Just use colors that go well with you're pony's name, characteristics, and cutie mark. For example, a pony named Midnight Sky who loves night should have dark colors like black,...