In the last few months I've spend a lot of time focusing on miniature design. Every mini born from a sketch. This is the very first step to take if you want to do a good job. The second one is block out. You should use simple form to create the final volume you want.
Then you can add detail. Remember THEN! The last is prototyping. That is the fun part. You see your character taking volume in the world. It's magic!