1. Eat plenty of food and drink the night before the race and get some rest. Eat your evening meal reasonably early. A good portion of pasta with tomato sauce or a rice dish, nothing too rich, will help you stock up on extra carbs.
2. I recommend eating carbohydrate rich foods like pasta, rice and jacket potatoes in the three days leading up to the run. Don't eat anything different, now isn't the time to sample new dishes, wait until after the run.
3. Sort your play list. Download plenty of soundtracks that will motivate and inspire you during the race.