You know how when you go to the hairdresser and you tell them you just want a bit cut off, and then the stylist goes wild and chops off five inches?
This can happen to your manuscript. By you.
See, we're not supposed to flood the beginning of our manuscript with backstory. I learned that tough lesson with my first completed manuscript. So what did I do on my second?
Cut out all backstory, jumped right into the action and finaled in a contest. But I didn't sell because the loss of backstory, the loss of me sitting and thinking and writing all about my characters' pasts, changed something in the story. It messed with my characterization. I ended up with a barebones chapter that left contest judges (as well as the editor) scratching their heads over my characters' goals and motivations.
Now I'm revamping that story and trying to think about who my characters really are. I'm a pantser so character charts, interviews, etc. tend to make me feel crazy. But I'm real good at daydreaming, and so that's how I get to know them.
How do you figure out who your characters are? What tricks do you use to create well-rounded people? Have you ever taken advice and jumped to the opposite extreme (like I did)?