If you are unsure of your cooking and camping abilities, nothing wrong with setting up the tent in your backyard and pretending you are on a weekend trip. If you choose a rainly weekend, it will really give you a good idea of how your gear works and what it is like to spend a night in the rain. If gear fails, you simply go inside! You could also do this car-camping. Once comfortable with the simple mechanics of camping, then venture out on a short (5 mile or less) overnight. Start out on a well marked trail, but get the map and pretend the trail signs are not there. Have the map out ALL the time, look at it, figure out where you are. All that said, the easiest is to find a mentor who will take you under thier wing. Here is where the organized hiking groups are the best.

Have you ever fasted? Simply going without food for a day and realizing you are not going to die is a great confidence builder.