Tbh, it depends what welder youd want to use, MIG is small wire feed, used for your thinner materials. arc is usually somewhat like using battery cables, you have a ground, and you have the positive in which you put your rod, but they also make wire feed arc too. then you have different rod sizes depending onthe thickness of metal in which you're welding. then you have temperature settings (amount of electricity used to melt the rod/wire).
Youve also got to be able to clean and grove what you're welding.then yes id have to agree with a few posters. the puddle is the form of the weld you need to learn. and practice is the only way to be good at it.
You can read all the books you want, i garentee your first welds will look like ****, and your rods will stick like crazy till you get it down.
Buy a cheap arc would be my recommendation. at low temps with thin rods you can weld sheet metal, higher temps with thicker rods you can weld car frames.
Also remember to get the right gear, and wear the right clothing.
A welders mask and welders heavy thick gloves do the trick, the helmut so you dont burn your retnas, and the gloves so you dont electricute yourself, and if some of the melted molten metal falls on your hand, and it will, you dont get burned.
Wear long sleeve shirts, the heat radiating from the welding can give you a really bad sunburn.
I made the mistake onetime of welding with my shirt off, and had just the gloves/helmut, it was the worst sunburn i ever had, all over my arms and chest, not fun.
If you have any questions, feel free to ask, im quite experienced in the field.