I just concluded my collegiate running career this past spring. Two weeks ago I went to watch a group of old teammates at Chicago, and am starting to get the marathon itch. Since the spring I've been training on and off- some days I'll run 10 miles hard, some days I won't even think about running. The break has been good because I was injured a lot in college during the track season and I need to get refreshed.
Anyways, my question is: what is the best way to transition to marathon training from collegiate running. I ran in a fairly conservative (albeit successful) D3 program, and I'm a high-mileage type, so I know the marathon will suit me well. I'm wondering mostly about logistics- how far out do I need to start training? How important is the race I choose? Do I need "tune-up" races? Should I practice running 26+ miles in training (it seems to me the main fault of average Joes training for the marathon is their never having run more than 18-20 miles)?
Any advice is appreciated.