What would I tell my 18 year old self (that would be in 1985)?
1. From a life enjoyment perspective...I'd tell myself NOT to live at home during college. My Dad died a couple years before that, and my Mom wasn't ready to live on her own. She made me a deal that she'd pay for my college if I went to the local university in town and lived at home to help her out.
In retrospect, I totally missed out on the college experience. Looking back, I'd tell myself to tell her I'd agree to go to the local university and be in town close to her to help her out, but I would NOT live at home. Even if it meant holding down a second part-time job, or sharing an apartment with a couple other people. I believe college is a time to get away from the parents and start your own life, and I missed out on that. I feel so strongly about that, that if I had kids, I would forbid them from living at home during college, or even going to school in the same town. I'd want them to go off and start their own life and start experiencing things on their own. I would even encourage them to go to school in another country in order to broaden their horizons beyond just the US.
2. From a career perspective...I'd tell myself to work a 9-to-5 job, in a cube, in an office, working for somebody else, for no more than three years or so. See how the "real world" works, and how you're working for other people making them money. You're "earning" money but not "creating" wealth. After those three years, get the hell out and form your own business with a couple partners you trust. It could be consulting, contracting, real estate, whatever. But find something you can do yourself or with a couple others (I work better as part of a small team with others to bounce ideas around with), own your own business, be the best at it, and grow it. Don't sit in a cube for 25 years working for other people (a lesson I learned too late in life).
3. From a financial perspective...invest a few thousand dollars in Apple stock each year and let it ride.