Another common mistake that people make after a wreck is they think they're fine. They settle too early. They don't go get medical treatment. They worry that, "I'm not sure if I really need to get checked out," and so they'll wait a long time before they'll go to the doctor.
If you've been in a wreck and you have any kind of injury symptoms at all, go get checked out. It's much better to see a doctor and let the doctor tell you, "There's nothing wrong with you," than for you to have a serious injury that you ignore and let get worse.