Strength training can be the greatest thing in the world. It works best, however, if you can avoid certain traps. These include:
1. Lack of focus. Don't just wing it. Have concrete plans every time you lift.
2. Poor form. How you lift is just as important as what you lift. Never compromise form.
3. Too much weight. This is the beginner's greatest sin. Don't fall for the "heavier is better" approach to lifting.
4. Too little weight. Your muscles need oveload to stimulate new growth. Try to lift weights on a progressive basis.
5. Overtraining. A typical training session should last no more than an hour and a half. If you're doing more than, you're probably overtraining.
6. Too many sets and reps. Ideally, you should give each body part between 3-6 sets total. And if you're doing 25-30 reps for each exercise, you're probably lifting too light.
7. Not getting enough rest and sleep. For your muscles to grow, you need time to recover. This means sleep -- and rest days between workouts.
8. Failing to warm up. A warmed up muscle is a more flexible muscle, able to lift heavier weights. Warming up will greatly reduce your chances of injury.
Beware of these dangers!