One writing technique that can breath some life into your story and also give you a whole bunch new story stuff to play with is giving your characters contradictory goals.
I've talked a lot about contradictions with Trigun--that's because the writer of it, Nightow, is great at them. Look at all the irony in his characters, their relationships, and roles. Ever since his protagonist, Vash, was a child, he's had contradicting goals. He wants to save the spider and the butterfly, which is impossible. If you cater to the spider, it will eat the butterfly. If you save the butterfly, the spider will die from starvation.
Again, it makes Vash complex. But do you see how by giving him contradictory goals, Nightow has just opened a door to a bunch of new plot and character fodder to play with? It give you a whole breadth of plotting and characterization that you wouldn't get otherwise, and it's what makes Vash, Vash; it's what makes him so different from other characters.
As I pointed out in an earlier post, Wolfwood's got contradictory goals too. He wants to save Vash, but he also wants to save the children in his orphanage, but because of his employers, he can't do both. Because of these contradictory goals, we get to see a deeper, more conflicted layer of Wolfwood.
So, try giving your character contradictory goals. How does he deal with them? Does he try to solve both like Vash? Or pick one like Wolfwood initially did?
Contradictory goals can help make your plot and characterization rich.