As part of a long-term project, I'm trying to compile training programs for races of various distances (half-marathon, marathon, 50-mile, 100-mile, etc.). The content of these programs will be dynamic (and will hopefully improve over time). The first installment is below...
Here's the basic framework for training that I used to complete my first marathon (the Karstadt Ruhr Marathon in Germany). In my opinion, it's quite a good plan -- if you complete the four-month program, you'll definitely be ready on race day, and it isn't overly demanding on your time (less than 10 hours per week, even during the most intense training segments). This schedule is based on the one put forward in "Run Your First Marathon" by Grete Waitz and is specifically tailored to novices with some running experience (i.e., people who are able to run 3–4 miles without stopping). It's recommended that you run one local 10K and one half-marathon race to familiarize yourself with race-day preparation. I chose not to do either of these because I had run a lot of 5K–10K races before, and it wasn't a problem.
The first three numbers in each week represent week-day runs, and the fourth number represents a long run on Saturday or Sunday. This training program allows for three rest days per week, but adding one day can be a good idea providing your body isn't showing signs of wearing down. After each run, try to allow for 10 minutes for stretching.
Week 1: 3, 3, 3, 5 (Total = 14)
Week 2: 3, 4, 4, 5 (Total = 16)
Week 3: 4, 4, 4, 6 (Total = 18)
Week 4: 4, 4, 4, 8 (Total = 20)
Week 5: 3, 3, 3, 6 (Total = 15, cut-back week, 10K race)
Week 6: 4, 5, 4, 9 (Total = 22)
Week 7: 5, 5, 4, 10 (Total = 24)
Week 8: 5, 6, 4, 12 (Total = 27)
Week 9: 5, 6, 5, 13 (Total = 29)
Week 10: 4, 4, 4, 13 (Total = 25, cut-back week, half-marathon race)
Week 11: 6, 6, 5, 14 (Total = 31)
Week 12: 6, 6, 5, 16 (Total = 33)
Week 13: 6, 7, 6, 18 (Total = 37)
Week 14: 6, 8, 6, 20 (Total = 40)
Week 15: 4, 5, 4 13 (Total = 26)
Week 16: 3, 4, 3, 26 (Total = 36, cut-back week, marathon race)
I'll just add two things that I learned two years ago during my training. The first is that as you approach roughly 12 miles for your long training runs (~Week 8), in-run nutrition becomes very important. You should plan on driving your running route beforehand to leave Gatorade and food that you can eat on the run (PowerBars, Gu, bananas, etc.). You'll probably want to take in some fluids and some calories at least every 4 miles. Everyone's body responds differently, but I have found that without in-run nutrition, my body tends to run out of glycogen (a.k.a. "hits the wall") at about 15 miles. You'll just need to experiment a bit to find out what works for you. The second piece of advice I can offer is that your running shoes will likely be worn out around ~Week 14 (between 300 and 350 miles) of your training. It's important to break in a new pair in the weeks leading up to the race, so that you can have good shoes to run on and so that you can be confident that you won't get blisters, etc. In Germany, I was too poor to afford new shoes, and it was just awful for my knees to run on shoes that were completely spent for such a long distance
As for the time, it's really not crucial. For your first marathon, finishing is the ultimate goal. That being said, it's helpful for your training to keep track of how fast you're running. For my first marathon, I finished just under 4 h (slightly under 9 minutes per mile). That was a very comfortable pace, but I still placed in the top 10% of finishers.
For more details, check back here later, or better yet, go buy Grete's book!