Anyone who’s taken a class with me knows exactly how much I despise character sheets. They’re evil and a waste of my precious, precious time. By the time I sit down and write with a character, he or she has lived in my head for months – almost to the point of my being schizophrenic. I know my main and secondary characters better than I know most of the actual people I deal with every day.
Where I’ve needed help focusing is on the tertiary characters. If a character doesn’t add to the story, don’t write them. But, if that waitress who’s only in one scene will add to the story, know a little about who she is!
Don’t worry about some silly sheet where you have to write down their dreams, goals, how many siblings they have, or any of that bull – but just one thing that drives who they are will come in handy.
We interact with tons of people every day and don’t bother realizing that they have lives too. That waitress who’s overly nice to children – maybe she lost a child a couple of years ago. That mean guy on the subway – maybe he just got bad news from his doctor.
The reader doesn’t need all those details, but something should be in your head, dictating how and why those characters act they way they do.
My recommendation is to watch a few episodes of Undercover Boss. Everybody on that damned show has a sob story. All of these tertiary people who only have tiny impacts on our lives but still affect our stories – they all have their own life and their own story. For the sake of your sanity, don’t spend a lot of time on this, but keep it in the back of your mind. There is a reason that people/characters act they way they do.