My friend Iggi did a panel at FAU again this year about designing characters and making reference sheets. She really added a lot more info since last year, and has uploaded the slides for everyone to see. There's a lot of good stuff in there! If you need help understanding where to start on making a character from scratch, or have a pre-existing one that you feel could look better somehow, but you're not sure what to change, definitely give this a read.

Character Design Basics by Iggi

The character that was designed by the class during that panel can be found here, too.