That's a big one.  I'd say if you want to be rich (and it would be nice to have a definition of that, BTW), stay far away from high-interest credit cards and don't buy anything that you can't pay cash for.  I've seen a lot of people fall into the trap of maxing out their credit cards, and then they're stuck with monthly payments that they can't ever seem to get ahead of.

Not having children is also a good idea in general, especially if you're young and trying to establish a career.  I think fewer people ought to be having kids, based on the lousy parenting I see from so many people, but they're also a cash sink that prevents people from ever climbing out of poverty.  If being wealthy is your goal, probably skip reproducing until you achieve that goal.

And yeah, start investing early.  That's one of the things I wished I'd done years ago.  I would also suggest investing in good dividend-paying stocks or index funds, but I'm by no means a financial guru.  Having an income stream from somewhere is very important, though.  I'm damn sure of that.

The last, and probably the most important thing I can think of for the average person is to invest in an education that's going to provide you with a solid career, i.e., going to college and majoring in one of the health fields, engineering, etc.  Computer science is a good choice, too.  Unless you're born with a head for business and have a serious entrepreneurial drive, you'll need a career that pays good money and it's very hard to get that without an education.  Oh, and pick a school that doesn't charge an insane tuition, else you'll be paying it off for decades.

Nice topic.  Disclaimer:  I'm not rich.