lol Gotta get that USP somehow. I'm not half as experienced as other writers here, but I think insecurities are great for character motivation. Satre talks a bit about how everyone has a sense of lacking and that people create projects to fill in the void. What motivates a particular football player, fame or the fact that he never got enough attention as a child? As a writer, I'll take the second one any day. It feels more genuine. That's what I mean about weaknesses -- I think true motivations often come from a sense of lacking. That doesn't mean that your characters shouldn't have strengths. Of course they have strengths, everyone does, but a character who has no flaws just tends to be boring. You want conflict in your story and you want your characters to struggle. Remember that they are fallible, it makes your characters more interesting.
Thank you, animenagai, that has opened up a very interesting avenue of thought and plot development for my trilogy. Very much appreciated.
In the novel, I'm currently working on my main character is such a horrendous b!tch that I dreaded writing the story for nearly a year. I realized it was because I didn't like the character all much. I spent some time writing as her and realized that aside from being a horrible, misunderstood person, she's also funny as hell. I got to know her better and now I love writing about her. I enjoy her horrible attitude. I suggest you try to get know your character better, too. Try to find some aspect of their personality that you love or at least like or else you will never fun with this project.
I think the only prerequisite would be that you can sympathise with your characters, no matter how different they may be.