THe half marathon is long enough to be a good challenge, but sort enough to really have some fun. And your first half should be all bout finishing with a smile on your face. If you are
1. Unless you have been running a while and have some speedwork under your belt, don't start while you are increasing mileage! You may throw in a few fartleks here and there, but nothing serious.
2. Increase the distance of one run each week slowly. Try adding a mile a week for a couple of weeks, then do a shorter run the third week. Bring up the miles the next week and continue the pattern. Many plans call to do at least one long run of 10 miles before the half.
3. Listen to your body! This is a MUST! If you are tired or hurt, REST! Rest is a very improtant part of training. Your muscles cannot adapt to the greater strain, if they are not allowed to recover. Learn your own signals and pay attention. For me: When my knees hurt, I probably need new shoes. If my hips hurt, I need some extra stretching. If I dont' feel like running--because I LOVE to run--I need a day off to rest.
4. Reward yourself. When you get out there and train when life gets tough, give yourself a pat on the back! When you reach a goal, enjoy a new toy--maybe running gear or new music to listen to while you run. Others are going to tell you that you are going to hurt yourself or running is bad for you, let them talk and move on. Running is healthy and when listening to your body, you can run for years to come. Studies show runners have decreased incidence of arthritis in the knees than non-runners.
5. Those long runs, run slow. If you think you are running too slow, you aren't! Running slow allows your body to get used to spending time on your feet. Running the long runs too fast will increase recovery time and increase the chance of injury.
6. If you are feeling ambitious and you have no signs of injury or over-training, throw in a few fartleks on your easy run. Runner's World has an article here that discusses a couple of ways to incorporate speedplay. Keep it faster, but don't go all out.
7. Ahhh, training diet... This is a do what I say, not what I do item. Running uses carbohydrates stored in the muscles. You will need to eat carbs, but try to make sure they are healthy carbs--fruits, veggies, whole grains. (This becomes a different story a few days before your race!) I confess that I am as addicted to sugar as I am to running. I have to remind myself that quick carbs do not provide the long term energy I need to run or give my body the proper fuel to recover. I am a work in progress on this one.
There are so many things that can change as you train for your first half marathon. That is part of the fun! Learning to adapt and get to the start line trained and healthy is a balancing act. Yet it can be done. Just remember, you would rather be a little undertrained than overtrained.