i learnt to weld when i was doing my apprenticeship and we did all sorts of stuff inculidn arc, mig and the gas stuff and further down the line they were taught how to do the other stuff as well

if you want to do diff welding then you need an arc welder

for everything else mig is fine

just watch out for the splatter of pidgon poo after your first attempt

it's good to practise with laods of different thicknesses and then rememebr what settings you were using for what

it's also worth remembering that if you are crap then get the correct settings sorted before you start welding the proper stuff, so find a scrap of metal the same thickness as th eone you want to weld and get it right on there before you start on the actual bit ofmetal you are welding

it may look easy but it takes an age to get right, i took a month to do one sill on the sierra, but i did seam weld it from floorpan onwards