Abstraction is fairly easy to good artists like you and me. Half of the battle is knowing colors, which you already have a fundamental understanding of.
Abstraction is taking the purer essence of a subject matter and manipulating it in a way that makes it nearly, or completely impossible to recognize without being informed. Breaking things down to its basic shapes, keeping colors in mind, and making a well developed concept all around. Look at my many face collection, they are abstract but remain objective. For you, you would probably want to create objective artwork so that your OC is recognizable but unique, so you should study its form and think about ways to deform and manipulate it into a whole new drawing.