Study the course before race day. Course maps are often provided online but there's nothing quite like seeing the area physically. Race morning is your first and only chance to study the general layout of the area so use this time wisely.
Rules and regulations vary from one race to another and you are in danger of losing points, or even disqualification if you don’t play by the rules. The race directors will give you a briefing on the race rules and you can usually download a rule book online but there are no second chances. Drafting rules for example vary, and there are rules governing whether a wetsuit is permitted so be sure to read the race handbook before you arrive and listen to the briefing and all announcements made on race morning in case of last minute changes.
Know your pace
You need to take each leg of the race as it comes. However, set your pace and resist the temptation of hitting the course too quick, which could make you burn out even faster. Use a heart rate monitor to determine whether you can push harder. If you have reached your threshold you can make decisions on whether to hold back or continue at a steady pace.
Set your race plan
A race plan where you anticipate the way you will respond in different scenarios, will help you set goal times. You will need to decide when to breakaway or stick to your own pace.
Hydration and fluid intake
Have a planned approach to food and fluid intake during the race. The best time to rehydrate and refuel is at transitions, and on the bike. Follow a regular pattern of eating and drinking, and ideally have your plan worked out in advance so that you simply follow the plan by eating/drinking according to time on the course. Carbohydrate rich food is what you need, but during exertion the body will refocus energy to digestion so choose high GI carbohydrates or better still, choose those sports energy bars, carbohydrate sports drinks which are specifically designed to help fuel athletes on the go. Your fluid needs will vary according to the environmental conditions and whilst you must not let yourself feel thirsty (you are already dehydrated by then) you also need to balance your liquids as you can make yourself sick if you take on too much. Until you've had some experience at racing and finding what works best for you, it would be prudent to get some assistance from a nutritionist, your local tri club, or join the TriathlonOz Forum
to get advice from others.