Real estate would be good to do.
Even if you stop doing it for a career, knowing how it works can help you in your own investments.
As for the rest of the things you are looking at, try and focus on a trade/career that you could do on your own if ever there was no "job" to go to. My son-in-law is an electrician and he's built up a great side business through friends and contacts that he's made. His boss knows he's doing it. It's stuff that the company normally wouldn't bother with.
It occurred to me that someone will always need an electrician.
I think the difference is that you can get rich in real estate if you do it right.
I wish I was in a position to build a real estate empire.
I'd need to do it with a no-money-down type of deal to start with. - I just don't want to buy it from a guy that also sells web-marketing programs on TV in the middle of the night.
I'm not averse to risk, though. I pulled the trigger on this house while not having a buyer for the old. I ended up carrying the old house for a few months while everyone tried to low-ball me thinking I was desparate to sell. Invariably, I just asked them if they would rent from me instead. They either went away or came back with proper offer.
Sorry, off topic there, but real estate can be fun if you're in the right spot.
Xl, if you're looking for a pupil interested in real estate for investment purposes, I'd take you up on it.