You might want to see if you can get this program from your local library or friends who may have already purchased it. But I've seen good results from parents who have used this system: http://www.thetotaltransformation.com/
Some tips for you are to stay calm, keep your tone calm. She's going to escalate into screaming and tantrums and if you follow her up the escalation chain there is no going back. That doesn't mean you ignore her as if she doesn't exist, which can also trigger her to lash out and escalate ("How dare you ignore me!").
If she starts escalating try different ways to help her calm back down. Sometimes asking the child to have a seat, to try to put what they are feeling into words, or even squishing Playdough in their hands until they can get the words out can help.
- Engage, listen and remind her of that: "I hear you."
- Repeat what you've heard, being sure to capture the emotions: "You feel angry because you can not go to the movies tonight. I would feel angry too."
- Remind her why this negative event has happened: "Do you remember being told that if you didn't clean up your room before 4pm that you wouldn't be allowed to see the movie?" You're not placing blame, but you're reminding her that she had a part in creating the situation.
- Encourage her to make better choices: "If you clean up your room before 4pm tomorrow, you can go see the movie tomorrow."
- Redirect her behavior by giving her options: "Which would you like to do now, A or B? (color, read a book, play a games, take a walk, whatever, something healthier than throwing a tantrum).
Sometimes you have to call for a time out, for either you or her. Grab a timer or turn on a timer on the microwave and say "We both need five (or 10) minutes to calm down before we talk about this any further. When this timer goes off, we'll pick this discussion back up (in the kitchen, the livingroom, some place that feels neutral)." Then, don't spend your 10 minutes stewing. Find your calm place, do deep calming breaths, pray, count to 100, say the alphabet, whatever helps slow your mind and calm your own anger back down.
Remind her that hitting is NOT ok. Give her the Playdough to squish in her hands like dough. And as she calms down and gets some of the adrenaline out of her system, ask her to try to verbally tell you what she's feeling. By asking her to use verbal words you're asking her to use a different part of her brain, a more advanced part of her brain, than the part where the rage and hitting is coming from.
For kids her age that can be tough because they may not know enough words to be able to express what they are feeling. You might need to print a list of feeling words off the Internet and start teaching her new emotion words. You should do this while she is in a calm time. Make it like homework. Can she pick two or three of those words every day, tell you what they mean, and what made her feel that way today.