Read the sticky on "New to racing? Read this" at the top of the
Road Racing Forum.
Botto's simple steps are like comparing pictures to words. Each picture is worth 1000 words. The very simple and straightforward text captures exactly what many racers do in order to become "successful" (definition varies) racers.
I would start off by doing as recommended, finding some group rides and doing them. Start as soon as you can.
Do early season races. The racers aren't quite as fit, they aren't "race speed honed", and typically don't "peak" for what are normally considered leg-opening rides. In your area I'd do Red Trolley (Feb 5th) and other events like it.
Don't be afraid of being embarrassed. In crits you get lapped, you drop out, and if you go cool down elsewhere, change, and come back, no one will think anything of it.
Although I was extremely afraid of embarrassing myself at Red Trolley last year, it was okay. I live in CT, we normally don't start racing until March, and we stop worrying about races being snowed out in mid April. So for me, at the end of an extremely intense training period where I basically rode myself into the ground, I figured I'd get shelled by the Cat 3s in SoCal. This wasn't the case, and although I couldn't get into a good position for the finish, I only lacked that last lap punch. I figure my training fatigue, lack of local knowledge (who to follow etc although I seemed to call it pretty well on my own), and lack of racing earlier (there are other events before Red Trolley) handicapped me.
The one exception are the Masters. They absolutely fly, with some of the best riders in the US from the 80s living in your area. Thurlow Rogers is incredibly strong, an all rounder that I'd compare to (relative to their respective peers) maybe a Stuart O'Grady. Not the best sprinter, not the best time trialer, and not the best climber, but 80% of the best in all of them. And that's relative to the best in the world. If he was 28 he'd be either a short stage-race leader or a super domestique like, well, O'Grady. Or even Voigt.
I wouldn't worry too much about your fitness. That'll be fine. I'm sure your cardio system is fine. You need to get in some high speed and high effort training, and the best way to both learn and do it is by racing. Just race. You'll be fine. Give yourself 5-10 races before thinking about giving up. 10-20 group rides.
Good luck and hope to see you at Red Trolley (you can watch me get absolutely annihilated in whatever race I do),
cdr
Oh, gratuitous helmet cam clip from Red Trolley I took. The guy that I point out for good riding got 4th and apparently upgraded to Cat 2 shortly after this race. I didn't know him but I knew he could ride. Also make note of some of my criticisms. Common errors. My other helmet cam clips show other common errors (focus on the 2010 ones).