Very good discussion going on here. So I'll throw in 2 cents more from another body work newbie. Armed with a little knowledge, a 3 pound ball peen hammer, and a grinder a novice metal shaper can do a lot of terrible damage. I learned that the hard way.

On the other hand bringing a light body hammer and proper dollies with some information from u tube or a basic metal shaping DVD and a lot of patience some really nice work can be accomplished.