Pft, I don't even know if this will be helpful. Let's see what I left out... >_> Use dramatic colors! Soft colors are hard to see and barely even make a difference compared to flat shading. Never, ever use colors close to gray or black! Makes your character look like that threw themselves in a pile of dirt. Look at actual photographs to see where shading goes! (don't use my doodles for a reference for that since I just slapped crappy shading on. >_> If you do, you have been warned... Do that at your own risk.) Using Photoshop helps enhance your colors! : D It's good to use, though in this instance I didn't, of course. This is for PaintTool Sai, but Color-Wheels are in just about every program so you can probably still use it if you don't have Sai.
Sorry this tutorial is so crowded. ._. I did it in a rush too. Don't be afraid to comment or message me in a note if you have more questions.
I'm also sorry if this tutorial was completely pointless and useless.
And if it wasn't insightful enough, I'll try to make a more useful one.