Anyone who's ever wanted to write knows how easy to is to put it off. NaNoWriMo was created pretty much as a way to conquer that. And you know what? The one year I tried it I quit on that too. I think the main roadblock I've hit for the longest time is that I know these characters, who they are and what they are about, but whenever I try to get an actual story moving I'm not sure where to go.
I watched Hancock last week. My main feeling coming out of that movie was "Someone had a really great idea... and didn't know how to execute it at all." My fear is that this is also my problem. There's a column that occurs on a comic book blog I read called "Storytelling Engines" where the blogger examines tv, movie, book and comic series and defines their storytelling engines, and how sometimes these things can get off track and that's often why a good show/movie/book series goes bad. I don't think I have my storytelling engine yet. So that's my first goal. Take another good look at these characters and decide what's the best coarse of action on how to keep them moving forward through various story archs again and again. OR, get one big predominating story arch and see it through to its completion.
When I start to get these pieces together, I'll also start looking for an artist. It's a long journey ahead, but as long as I don't push it aside and ignore it, I know I can get there.