Give her NO food besides dog food. When I said firm that's just what I meant. When she does something you don't like tell her so. "No!" in a quick, firm voice is a powerful tool. Dogs don't infer meaning to words as much as the tone you use when delivering them. She needs to know that you're above her in the pecking order (pack animals, remember), that you have a good side and a bad side and that it's in her interest to stay on your good side. The only way to do this is to RIDE her about the things she does that you don't like. This process takes time but the rewards are immense.
Also, develop a training schedule where you work with her. This will give her a purpose, dogs need to feel useful too. The process burns energy and will get her used to complying with your wishes. Hunt up some speifics on the type of dog you have and remember, be FIRM about how you want things. It's not easy, but stay with it.