Say you want to describe the perfect fantasy scene. An epic fantasy scene, even. Something memorable. So you describe the emerald grass in a little clearing in the forest, and the noses of the red and white mushrooms pushing up through the moss, and the sheets of golden light dappling the ground beneath the white-barked willows, and the roses, red as wine, the violets like amethysts... and the big, crap-encrusted toilet with a cracked lid sitting in the middle of it all, a centipede crawling out of its bowl. What are you going to remember about that scene?
Your character is that toilet. Or rather, your character is the whole scene, but every character should have a toilet to call its own. And depending on what form that toilet takes, your character will be perceived differently. But where to start? Because a toilet alone is not enough. That toilet needs that forest just as much as the forest needs the toilet. And what will make both interesting is the person who needs the toilet. And... umm... why.
That's Not a Flaw, It's a Feature! Your character has a problem. Otherwise, why write about them? More important than your character's name (which is totally deep), or the intensity of their ice blue eyes (just like Olivia Wilde's...), or the cheese-grating utility of their rock-hard abs (here’s looking at you, David Beckham), are the questions at the heart of your character. The fears and desires that keep them up at night and that drive them to do such novel-worthy things.
In Divergent, it is precisely Beatrice’s flaws—not being selfless enough, not fitting in—that allow us to identify with her in a society of seemingly robotic people. But it is her desire—to be herself in a society that practically makes it against the law—that makes us love her.