You say that you have been a long time cyclist but are just now getting into racing. I know that when I first started racing, I had already been riding with other racers for a while. Find out what category racers your riding mates are and how you compare. When I started racing, I knew that I was stronger than the rest of the 5's already, and won a bunch of races just by breaking away solo with about 3-5 miles to go. That's as simle as it gets.
That leads to another very important tip. BE CONFIDENT IN YOURSELF. If you're not used to racing, you may be surprised at the pain you will sometimes experience. You need to remember that everyone else is going through it too (unless you're doing long senseless pulls at the front...) and that they probably have it WORSE. Going into a race with the feeling that I was going to win, and that I was the strongest rider in the field (even if it was very far from the truth) always helped me out. Racing is a mental game.
Tactics tend to be completely nonsensical in most Cat 5 races. When a rider breaks away, there will be so many riders who try to go with the move soon therafter, that the whole field will respond. The most dangerous and likely to succeed moves will come in the form of counter attacks as a break is just being reeled back in. That is your time to go if you have the legs and the inclination to do so.
NEVER let a break get out of sight in a Cat 5 race. To most Cat 5's -- out of sight out of mind. If a break get's out of sight then the field will give up and fight for the scraps. This type of thinking isn't present in the higher levels of racing. This is also a reason why, if you find yourself in a break, not to hold any efforts back. Don't pace yourself easily in a break as though you might be out there a while, pile on the effort as hard as you can IMMEDIATELY to get out of sight, becuase if you mannage that, you'll be in the winning break.
- Maurizio