Warm-ups

Stretching is not a warm-up. In fact, no studies have proved that stretching prevents injury. However, some studies have shown stretching prior to exercise or athletic activity can weaken the muscle, which may lead to injury. A warm-up is actually a low-intensity dress rehearsal of the movements performed in an activity. Save the stretching for after the workout.

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Perform a Balanced Workout

Think of muscles as a corporation. If one person overworks, the others feel that they don't need to participate. They become lazy and apathetic, whereas the overachievers suffer from burnout. The same thing happens in your body. If you overwork some muscle groups, they burnout and suffer injuries. The under worked muscles become lazy, and eventually atrophy. People often perform more chest exercises than back exercises, more quadriceps exercise than hamstrings and more biceps exercises than triceps. Balancing muscle groups is crucial to injury prevention.

Don't Subscribe to the "Too Much of a Good Thing" Philosophy
When weightlifting, be sure to give your body 48 hours for recovery. For cardio, vary your routines, so that you are using different muscle groups. Gradual progression yields better results.

To prevent injuries, exercise smarter, not harder.