Michelle at Magical Musings has an excellent post about dealing with orphans -- not the parent*less child kind but the character that pops into your head and wants to play kind. I love it.
When I realized five x three chapters, while good writing practice, wasn’t actually getting me a completed manuscript, I made myself write a one to two page outline before I started writing any idea that came to me. If this idea could sustain a beginning, a middle and an end, then I gave it permission to take over my brain for 5 or so months.
So simple, yet such a "why didn't I think of that?" sort of thing.
Now I have a plan for those guys. And maybe I'll have a few less characters in my head for a change.