I have done 2 centuries in the last month. I did them solo (not organized). Here are my insights:
1. Hydrate yourself really good starting the day before century.
2. Eat right starting the day before the century
3. Start out slow for at least the first 25 miles... pace yourself.
4. You should be able to complete a metric century without being totally wasted at the end of the 64-65 miles before you attempt a 100 mile century.
5. Make sure your bike is in perfect order and bring spare tubes and the appropriate tools.
6. On the ride, eat your snacks and drink before you think you need to.
7. Post your results here and have a great ride!!!
Later,
Ti-Carbo