Get a good MIG welder, so you can use flux core wire or actual metal inert gas. There a lot of posts on TBN about welder models and types. I think the wire is most flexible and easiest to use. We have MIG, wire,TIG/stick and gas. We use stick for heavy stuff and wire for everything else, seldom inert gas. Mild steel doesn't need it. (I'm bad at all of them. Not enough disciplined practice,)
Search of the customization and build it yourself forums for a lot of good info.