Source for Creating Characters: Yourself.

Your first, best source for characters is your own personality.

Writing For Comics & Graphic Novels with Peter David, page 46

When creating characters for your stories the greatest challenge is making them "real". Personality traits. Flaws. Character tics. Take your pick. But did you know you can add something really cool to your characters...Yourself.

Well, not all of yourself into them. Just bits and pieces. Your past to your experiences as a high school teacher. We writers invest aspects of ourselves to create identifiable characters in a manner of ways. For instance, Diana Rowland has poured in all her years in law enforcement for her Kara Gillian series, giving it the realism not all crime solving/urban fantasy books have. Comics icon Stan Lee would tell you about the "origin" of Spider-Man from his teenage years when he was, to a degree, a lonely kid desperate for acceptance.

When writing my own stories, I've plucked a few things from my own personality to add to my characters, and some were without even knowing it. I named a character Andre McDyess ("Andre" short for my name; McDyess after former NBA player Antonio McDyess). Plus, I gave him five percent of my sense of humor. My superheroine in a comic book series was crafted from my experiences in a US History course at a community college, and I equipped her with some of my own quirks, like coffee and Pop Tarts for breakfast when on the go. Sorry, no super powered mayhem involved. One of my most flawed aspects I'm not proud of is being a smart ass. That's what I share with another one of my characters because let's face it, we all have that one friend or relative who'll shoot his/her mouth off.

The more honest you are about yourself, the more you can give readers something to identify with in terms of characterization.