RE: DIY Welding
well it depends on the thickness of what you are gunna weld. if its like the thin aluminum like on a baja you could use a mig welder but the welds wouldnt look very good.
i would recommend a tig welder, most likely a finger tip control type. its easier to use of the 2 types of tig welders. the other kind is what i have. i have a pedal control tig welder. a big one at that. the good thing about a tig welder is that the welds look good enough to show without grinding them down. but thats after you get good enough to do that. i still cant get a perfect roll of dime with a tig... so it takes practice.
a tig welder is easier to switch between steel and aluminum, b/c all you need is welding rods and gas to switch with a tig welder. or at least mine.
a mig is more complex to switch out.
what i can tell you to do for a diy welding is to practice, get a feel for it. practice on a variety of metals. with a tig you just feed a little welding rod into the pool of metal and draw little tight circles in it kinda fast but you just need practice.