Here is a great article on 6 essential tips for your best race ever, according to Mark Allen:
http://www.active.com...
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1. Overdo Distance and Under-do Speed: You are an endurance athlete. What you need most is endurance. Within your grab bag of favorite workouts should be one key swim, bike and run workout that stands out above all others.

2. The Taper: Just about every athlete alive knows how important tapering down for the big event is, but very few actually do it.

3. Sharpen Up: This will be your final main speed session to shake the bugs out before you go into cruise mode for race week.

4. The Last Three Days: These are the most important days leading up to your race.

5. Eating and Drinking: Three days out is the time to start loading up for your race. Humans are not like camels. We cannot absorb big volumes of liquids.

6. Race-Day Secrets: Ah, just what you've been waiting for.