This page has all the references I've made of my characters. I have a general format I use - one fullbody on the right, some handwritten info to the left that outlines age, height, sexual and gender identity, a handful of personality details, and their powers. If further explanation is required, I add another box off to the left with that information, as seen with Viktor, Mocha, and Vince.

When making references, I like to put the name in an approximation of the character's handwriting. It adds a bit more uniqueness and personality to each reference.