Starting any training program requires a great deal of time and commitment. Preparing to run a 13.1 mile half marathon distance requires a twelve week training program. You should be regularly running 10-15 miles per week prior to training. Its always a good idea to consult your doctor before starting anything as strenuous as training for a half marathon, especially if your over the age of 35 or 40.
With that in mind, below is a link for the training schedule that I have used in the past for my races. www.coolrunning.com/engine/2/2_4/134.shtml
This training program is effective and helpful for beginners. Here are some more tips to keep in mind during your training.
Especially for beginning runners or those who may be experienced at running but training for their first half marathon, it's important to take two days off from running during the week to allow your joints and muscles adequate time to rest.
On your weekend long runs, make sure to bring plenty of water to drink after your run and during your run. It's important especially when your long runs start reaching distances of seven, eight and nine miles or longer, to have water at the mid-point of your long run as well as at the end. Sports drinks such as Gatorade or Powerade are fine as well, but you can't go wrong with water. Also, this will get your body accustomed to what your race conditions will be like, when you'll be able to have water most likely at every two miles in the race.
Walking & Taking Breaks
If you feel the need to walk or take a break in your long run or during any of your training runs, by all means don't feel guilty or hesitant about doing so. Especially for beginners, the goal is to complete the race more so than to compete, and when finishing is your goal, it's perfectly fine to take walking breaks here and there. Listen to what your body is telling you, as it's quite possible that perhaps you're trying to maintain too fast a pace.