A company that I was going to change jobs within to get out of retail offered to teach me some welding and machining. I sent several days learning how to TIG weld steel and aluminum and how to set up the milling machines to get them back to spec. (pneumatic nailers/staplers). I picked up Iron/steel really fast in that the heat range is very wide and metal is forgiving. Aluminum on the other hand is quite difficult with a very narrow working range from popping and sizzling to puddle on the floor.
Also of note, the man teaching me thought it was funny that he hadn't told me to wear long sleeves and such, it was sort of a hazing thing they did. The issue being I am a fair skinned redhead that burns easier that most. My neck, upper chest, and inner arms were burned purple one of the days I was learning and ended up having to be out of work for a while as I recovered.
As a side to that, where welding steel is easier than aluminum, by far...the HARD and artistic aspect is making those welds look good. The method we were using just had to be solid, not pretty...such that it could be milled back.