A couple people asked so I figured I would make a post about it :) Steps I take in creating a character for 3D, illustration, animation...
-Just focus on one thing at a time. For example start with drawing your characters in b/w with just line thinking about anatomy and how a human body moves naturally. How will your character stand, does he stand up strait or slouch over?Once you feel like you understand the basics of line and human anatomy in your character, then focus on values.
-Paint your characters in just b/w wile studying realistic light and shadow and how it effects the form.
-Then move on to color. Study from life and look at color zones of the human body.
Study color schemes and be smart about how colors react with each other. Mood is very important here. Is your character happy, sad, depressed, evil, sweet...? If you are drawing a happy character his colors will probably be more saturated, bright, warm. Apposed to a depressed character - darker, less saturated, cooler.
Very simple ideas but I hope this is helpful.
A lot of the work I do deals with color and giving a modeler a good colored/believable design model from.
Chris Oatley goes into more detail with emotion, and creating a "real" character. Check it out!