I can only add to what the others have posted - He needs to get a very well rounded experience working with metals. Not just welding - but learning Metallurgical Engineering will give him a career that will have headhunters seeking him out. Not that he needs to be in the top of his class in this field, just to give him the experience with welding and working with the different properties of metals. There's a huge difference in welding on AR400 steel,  common mild steel and stainless and component's of those . . .. 

From there, as someone posted - learn to Tig weld and here's why . . . . . 

Lets take pipelines - the guys that prep are lower payed of the crew, then the line welders welding joints - all working in the open elements. Tig welder, well, not only are they in great demand, they are the highest paid. They get the enclosed heated and cooled areas to work, as typically, tig welding is the most precise of all the welding and that process and components need to controlled.

He needs to get a few years to develop his skills, as someone pointed out - farmers are going to bring him the crappy, hard jobs to repair . ... otherwise they'd weld it themselves.

Edit : spelling / clarity