Get a LOT of money first. If you want to road race, do some karting. Skip Barber is a good investment school wise. Autocross. Talk to everyone you can and get your name out. But you have to win, a lot, for anyone to care. Once again MONEY. Get your SCCA license, rent a car, and win. ALMS is not cheap, just to run Sebring it would have costed me like 40k. The better you get, the more support you can pickup. But to get PAID to race is hard in the US road race wise. If you want to race as a career don't waste time building your own car, rent one, or buy one semi built or ready to go with a good history.

If you just want it as a hobby, go autocross, join the SCCA and do PDX sessions (one this Sunday at Road Atlanta, come out and see how it works), just have fun. SCCA is a great place for a hobby or people moving up a ladder. Def. the best racing club in the US I think.