1. Make sure your bike fits you and is comfortable. Ditto clothes - take what you may need.
2. If there are hills on the century course, make hills a large part of your training miles.
3. If you can easily do 100 miles per week, then you can do a century. No need to ride longer than 50 miles in trainng, but a lot of your rides should be 40-50 milers.
4. During the century, start slower than you think you should, then slow down! Don't get caught up in all the excitement and go out too fast. Your race, your pace. Read this advice again, then read it again.
5. Eat, drink, eat, drink, etc. If you feel out of energy or feel that you're 'done', it's a food and drink problem. Oh, and make sure you use electrolites in your drink, or what you eat.
6. Cut the century into pieces: Your first goal might be mile 25, next the upcoming rest stop, then another achievable milestone, etc. Makes it a lot easier than counting down the whole 100 miles. Rest when needed, if needed.
There's nothing magic about a century - it's just a mile done 100 times. Anyone can ride a mile! You can and will do it. The biggest obstacle is your mind; once you do your first century it becomes clear how easy they actually are. My goal for this year is to do the Tahoe century, and that's part of my recovery plan after haing my pelvis smashed in a bike car acident last November. Last year I did the same century - being off the bike for the month after surgery. Oh, and I'm 73. Like I say, you CAN do it.