I presume you're starting at cat.4.
Take care if its just cat.4 only, there will be some numpts who cant stay upright on a bike or hold the wheel.
Watch of for the semi-inevitable crash leading up to the sprint finish.
Is it a road race or a closed circuit crit? It would make a difference to my tactics.
For a crit (esp if its cat.4) I'd be tempted to have a few attacks off the front to see how strong the rest of the field is. If its cat.4 only then the field is unlikely to be super strong. I rode off the front of a cat.4 crit race relatively easily, where no one was too keen to bridge the gap.
A Road Race will be tactically different than a crit. Is it a cat 3/4 or 2/3/4 race?
If its a 2/3/4 just try and stick in the main bunch and use the race as experience, as in all likelihood it will be fast (cat.2s make a big difference compared to 3/4 only races).
If its 3/4 only, try and stay near the front (top 10), you will need to be aware that small breaks are likely to get away, whether they stay away is up to the actions of the main group, Some advice would be to sit in and not work, but at 3/4 racing I say get stuck in and do some work at reeling in breaks etc.... as long as you aren't knackering yourself out. Most flat races at 3/4 level will end in a sprint finish either from a breakaway group or main bunch. Position yourself near the front (which you should be already) and be in a position where you are a few wheels back coming into the final corner. Forget the organised leadouts when you watch the tour, sprints in 3/4 racing is much more chaotic than that. If you have a strong turn of speed then you'll naturally end up near the front. Sprints aren't that fast at cat 3/4 level. Avoid being mid pack at this point as there's always some near misses or a proper crash.
If its hilly then good luck as the pack is very unlikely to stay together.
One of the things that I wasn't prepared for when I started out was the internal politics that goes on in races. Be aware that the atmosphere can be very highly charged, more so that MTB or cross races, in my opinion there are more people in road races who think they've got a chance to win that you get racing MTB, as it can come down to a sprint finish. There tends to be a fair bit of shouting and swearing and sometimes pushing and shoving. Just keep your head down and follow the wheel of someone who looks confident on the bike. Try to keep off the brakes when you are close to others in the bunch, this will annoy the hell out of others and get you shouted at.
Watch out for the "I've been doing this for 20 years" guys that are usually more vocal with their instructions and try to boss the group around or try to police it. There's always someone more experienced than you in the group but don't think they are the be all and end all.
That's turned into a mini essay already.
p.s. stick to the MTB its more fun!