I'd suggest trying as many things as you can (mtn biking, too). Get to nationals if you can.
Try to network as much as possible.
The races are a lot easier than category races. I raced as a 1, and the As was way easier than a 1/2 race, unless Brent Bookwalter showed up. But then he'd just win, so the rest of the race would be okay. But if you're a 3 already, do the As. And if you're a competent 4, maybe do the As a well. Ride with the best guys as much as possible.