Just a very quick tutorial I made to help begginer artists to design characters. Actually, this is not really a tutorial at all, just a reference of colors to NOT put directly together if you don't want to hurt people's eyes by making poor color choices. If you have characters with very similar color palettes, you may want to read about the theory of colors to help you at designing characters.
I'm not going to explain the whole theory of colors, since I'm not too good at explaining and there are already plenty of tutorials you can find about it.
So here are two tutorials on colors made by others, containing very useful information that will help you in designing characters and even more: