I agree, I would highly recommend finding a piece of scrap metal, not even an extra panel, just something. Take a ball pin hammer and beat the hell out of it. Practice on straightening out those marks before you even attempt to put a hammer and dolly to your ride. Body work is really not that difficult, does it take time, patience, a keen eye and practice.....yes. But even the best body man in the world, started out just like you are right now. I enjoy metal work and fabrication, I've been doing it for almost 10 years now. There's nothing more rewarding that having a panel all beat up, that someone would rather replace than fix, and making it like new. Practice, practice, practice! before you touch your car. Learn how each dolly and hammer setup works together for each type of dent/wrinkle. That's why they give you so many and not just one hammer and one dolly. Each person has their favorite set to work with. After some practice, you'll find the one that best suites you. Just don't be in a hurry to get it done, take your time.