Always but weld you can't work a lap weld. Tig is the way to go the weld is soft enough to do some body work. Basically all you want to do is get your torch and rod lined up and step on it. The smaller the weld the better. Try and keep your heat zones as small as possible. Just tack the whole thing if you can't hold your hand on the weld you are welding too fast. You can start welding between tacks when you have about a 1/4" gap between all the tacks but same thing if you can't hold your hand on the weld slow down and let it cool. When you are welding though be fast don't take your time and try to make it look nice move quickly.