Ditto on eating before you ride. I usually eat a bowl of oatmeal & raisins or half a bagel and cream cheese, or a slice of toast with cheese or peanut butter. Just so you have something in your system- mainly carbs.

Bring more water than you think you need (2 bottles), and some snacks. For that distance, you may want to eat something around 15 miles in or so. I find that I want to eat a snack by about an hour in. An energy bar (luna bar or similar), pretzels, or trail mix are possibilities. A rule of thumb I've been using is that after an hour, I eat about 100 calories every half hour. I have become pretty fond of shot blocks as a ride snack- they are easy to eat and digest and they are like eating candy.