Rule#1 Ignore all who insist that you perform more than a hour of strength training per day or more than 2 hours of cardio per week in order to shed bodyfat.
Rule #2 If you have the mindset that you must reduce you calories to ridiculous levels <1000cals/day in order to shed bodyfat, you are doomed to become another statistic.
Rule #3 Understand that on a calorie per calorie level, all foods are not equal. Pay attention to foods that stimulate metabolism rather than curb it. Don't be afraid of food. Food is not your enemy.
Rule #4 Contrary to popular belief, weight training is catabolic, not anabolic. The anabolic stage occurs during a resting period when you are away from the gym. If you want to gain muscle you must keep your workouts brief and get as much rest as possible.
Rule #5 The gym is for building bodies, not for building relationships. get in, bust your ass, then leave. Don't get distracted from your goals. And if you're working out longer than 1.5 hours/day, chances are you're making friends, not building muscle. Remember, it's not how long you train, it's how hard you train.
Rule #6 Don't forget to smell the roses. There's more to life than whipping up whey protein shakes and going under the squat rack with 500lbs. Get out and enjoy other activities such as rollerblading, swimming, cycling, etc. Don't be a "gym geek". Have fun.