I'm no expert welder, but from what I know, get a gas shielded setup for much cleaner and controlled welds. Buy a bunch of sheet metal/old fenders from a scrap yard to practice on. After your welder, start saving up for a big compressor if you plan on paint/body work.
P.S. While I understand URY914's motivation in his response, I don't share his curt tone. Personally, if I needed to "save time" I wouldn't be reading this forum at all.
No offense intended URY914, I'm just sharing my 2 cents, not flaming.