okay, i'll start:
1) have fun (duh)
2) take out half the air out of your tires. feel what the pros use and add a bit if you're riding clinchers or are heavier
3) go to a clinic
4) bring a grill to the race - you'll have instant friends
while there are many ways to get off the bike, the two typical ways are to swing your (right) leg over and have it land behind your left leg, and then your left leg follows shortly after (people either have the left leg already unclipped and resting on the pedal, or unclip at the last moment).
the other option, often used for high speed barriers which are becoming a rarity in this sport, is to swing your right leg between your left leg and the bike, and it hits the ground in front of your left leg, allowing your body to be fully facing the barriers and hit the barriers in stride.
this probably deserves its own topic... start one and we'll find some videos to post to show the differences. hardly anyone does the step through although personally I got so used to it from the days of lots of barriers I do it most of the time anyway.
bring your family...they'll have fun watching you race
show up early and pre-ride the course (at speed)
if snots are dripping out of your nose faster than you can wipe them off...you are racing cross
if you aren't suffering, you aren't going hard enough
Grab a bike, some mayo and fries, smash your shin with a 2x4 and maybe get a tatoo, piercing and some variance of facial hair-ladies you are not exempt from this! Prep is over. Now ride, fast-for what seems like eternity. fall, get up, push-fix your chain, change a wheel and grab the dollar bill from the silver speedo on the superfan after the run up. catch your breath, avoid a dodgeball and finish...your lap, now do it again, but this time with your brakes rubbing and a small dog chasing you. Probably shouldn't have had quite so many beers and 'brats at the 6 A.M. pre race rendezvous, but don't worry only 4 more laps...now you are hooked, give up any rational thought for the next 13 weeks and next week, bring some extra coffee-
1) do 1000 perfect at speed dismount/remounts before your first race
2) run 3-4 times a week in the month before the first race then run once a week during the season - 30 minutes a session is good enough to return huge benefits when you are off the bike. Don't worry about (running) speed work unless you are a pro or only work 10 hours a week. The race is won on the bike, not the feet.
3) Low tire pressure is key
4) Clinics - get someone who knows what they are doing to help you master the technique. It isn't enough to self teach (in general).
5) just have fun
1. get a single speed (you'll have one less thing to think about and you'll get extra attention, meaning more yelling directed at you during the race, which is a good thing)
2. Apologize in advance to your wife (or husband). She's (or He's) about to see a lot less of you, and you'll be all banged up when she (or he) does. Let her (or him) know that the season only lasts 12 weeks (don't tell her (or him) about January races until after Thanksgiving.
3. Do all your training at 4:30 am. This is the coldest time of the day. Unfortunately, it'll always be warmer at 4:30 then when you actually race.
4. Wear something stupid at the race (then, if you get beat, fall a lot, quit, etc... people will just assume you're there for the party).