Remember to:

Get in a long run of ~10 miles 3-4 weeks before race day, at 2 to
3 min/mile slower than race pace

Taper back your daily milage-alot-in the week before the race

Hydrate i.e. load up on fluids, beginning the night before race day

Start out slow. Don't let your adrenaline get you out too fast in
the first few miles or you'll really pay for it in the last few

I've run 6 marathons and three or four halves and I can assure
you that the view is MUCH better from the back of the pack