I have taken to keeping a list of characters in each story that I write. It seems obvious but it's the only practical way to ensure you don't get the names wrong during the writing of your story. Unless you have a super memory of course.
I also try and keep a note of where they are at any given time. This helps to ensure I don't place them somewhere they could never be. Again this it brought to you by the society of the bleedin' obvious.
I'll see what other obvious tips I can give as I go along.