So my main cast of characters pretty much take different personality parts of myself. It helps me write them a little bit better. For example my main character has a really hot temper over really stupid things, and the love interest is easily attached to one person in specific. Those are two huge things that are a part of my personality, but I decided to spread it amongst the cast.
Otherwise I shoved a bunch of different stuff into each character from various people I have known throughout the years. It's always personality wise, and not usually visually.
They say to write what you know, and I knew a lot of people in high school. However, the type of people I knew were all really weird and goth/skater/druggies/scene kids, so that type of group element has leaked its way into my comic. Haha. Well, at least it'll keep it interesting.