Also, if you're welding sheet metal, you'll have an easier time using .025/.023 wire and getting some welding spoons, if the setup permits. Chill blocks, just pieces of aluminum or copper/brass placed next to the weld, might not be a bad idea either.
This is TIG welding stainless, but it does an excellent job explaining the concept. Short runs and back step welding will also help prevent the panel warping all to Hell. S/F....Ken M