agree. try to be smart and avoid as many pitfalls as possible.
no experiments on race day! aka
- don't change the food
- don't change the hydration strategy
- don't change your running clothes
- don't change the shoes
- pick a suitable pacing strategy and stick to it (don't start too fast)
- sleep enough before hand (the last night is very often short // you'll sleep badly, but that doesn't matter if you've slept enough)
- believe in the taper plan and stick to it
- avoid walking the day before / the day off the race as much as possible (especially in the big city marathons, people often have to walk several miles before they even get to the start line)
etc
but yes, especially at a first timer, from what i've read, chances are high that something will go wrong
but for many people it also works out perfectly, we'll know more in 20 days, hehe