"Good Eats" is a good place to go if you want a very detailed and in depth lesson on cooking turkey. One simple thing that works very well is to cook the turkey breasts down so as the turkey cooks the natural juices are, obviously, going to run down. If the breasts are on the bottom, they collect a lot of those juices keeping them moist and delicious. Also you absolutely must rest your turkey. I prefer to do it wrapped fairly tight in foil for about a minute a pound, up to 15-20 minutes. Keep in mind the bird will continue to cook while it rests so you should take it out about 10 degrees before its actually done, so use a real thermometer not one of those pop out deals.