I thought of another thing - if you plan to take fluids from the aid stations, practice. It takes some technique to get the water from cup to stomach without putting most of it either in your windpipe or on your jersey. Enter a shorter race that you know will have water stations, or ask a friend to hand you cups of water so you can practice.

Crease the cup to create a spout, tilt your head to the side, pour the water into your cheek, swallow when your head's back upright.