Just to add another opinion to the mix................
I bought a Lincoln Mig Pak 15 about 10 - 12 years ago. Also got the gas kit for it.
I'd never welded anything before that. Had a good friend who told me that he'd come over once I got the unit out of the box and put together and show me how to weld! He came over and brought over a few pieces of scrap and showed me how to set up the feed and current range. We made some passes with things adjusted to get a good weld, then varied the feed and current so show what happens when things aren't set properly for the material being welded. After about 30 mins, he gets up to leave, telling me to just keep practicing with the pile of scrap he brought over.
Bottom line is that a class is good, but time with the gun in hand is what will make you proficient. My first real car project was notching/reinforcing the frame for my Fiero engine swap. The welds were functional, maybe not the best looking, but so far they've held up. After that I did a 30 x 10 custom kennel that attaches to my shop. Did the kennel with 1" square tube for the verticals and 2x2 and 1x2 for the horizontal members, all 0.080 thick. Kennel is a little mild, more like an open air prison cell if needed
Latest project is/was a full frame for my TVR. Before I did the frame, I made a heavy duty welding table that I could fabricate fixtures for holding the frame as it was being built. Also built a mess of fixtures/stands for holding the body, the hood, the engine and trans, and one to hold the TVR body upside down for additional fibergalss repairs.
On the pretty/sexy scale, TIG welds are the best looking, but a little sanding with a flap disc, a little filler before paint and MIG welds won't be noticed! Both are, within reason for the home fabricator using mild steel, going to provide the same result, TIG just needs more $$$ for the hardware. Yeah, I'm generalizing, but you might see where I'm getting at.
Hope this helps, YMMV, etc....
-jeff d