I find one of the hardest things to do at times is to keep my characters consistent. Usually if I write them all at once they end up being consistent but at times (like right now) when I'm not righting consistently the characters can suffer. I forget what they look like or what they were supposed to be doing in the story, I forget their motivation or the way that they speak.
The best way to combat this that I've found is to keep a separate note-book for all of the information that is actually just information instead of "story". I have a synopsis for each character which includes their Motivations, a little bit of their history, some notes about where I was going with them. I also have their appearances so it stays consistent from beginning to end. It's been incredibly useful when I'm writing (even when it's in a short period of time) as a handy reference to look back at. It's also a great place to keep the names of smaller characters.
Who wants to flip through the novel while they're working at it just to find a name that's mentioned once of a guard or something who made a ten second appearance? (Makes me go, why did I name that character again? He's never going to be seen after this...) By keeping track of who says or does what I can reference it easily and then I don't have to go through the story again. That's a good thing as far as I can tell since it does keep me writing at a relatively quick pace when I do write.