Before you start designing the characters for your project(s), consider reviewing these sources for guidance:
1. Great Character Designs—Tips on Creating, Monetizing and Popularizing Digital Characters
Discusses the qualities of the most enduring game characters.
1. Great Character Designs—Tips on Creating, Monetizing and Popularizing Digital Characters
Discusses the qualities of the most enduring game characters.
Numerous interviews with character designers and examples of their work.
20 useful tips to help you in the character design process.
Tips from a manga/anime perspective.
Head design tips from Krishna M. Sadasivam, creator of the long-running web comic "PC Weenies."
6. JohnKDesign
John K., the creator of "Ren & Stimpy," has a blog dedicated solely to his particular approach to character design.