Each and every character gets there own worksheet. Even the minor ones! I know what you're thinking. Why? The answer is easy. You never know when a minor character will become something more. Because I tend to write series based around families and friends I need to know a lot of the players before I start writing. The series arc helps with this, but I still find that I want to know more. Some of the stuff will never make it into the book becoming less important. Yet other things so small I might think they'll be unimportant could turn out to be a major issue at some point.
Along with the character sheets there is a few other things I need to do worksheets for. I will do a family tree and town map. If a certain home, restaurant, or business is important to the story I want all that info at my finger tips.
Now what happens to all this information? How do I keep it at the ready as I write? That's the next step. A Series Bible.