People read stories for characters. Characters drive the story forward. If your characters are flat and lifeless, your story isn’t going to be much better. The first thing you should do when putting ink to paper is to look at who will be telling your tale. What do they care about? How do they think? What drives them forward towards their goal and what is going to bring them back.
A map of your characters is a great initial map of your plot. Once you can get into the head of the people you will be controlling, you can start to figure out what situations they would be best suited for.
I found a great article in Suite101 about rewriting your stories for better characterization. It talks about point of view, strong verbs, slowing down the scene and showing reactions and it’s a great place to start if you are just learning about bringing your character’s to life.