Precautions you should be aware of before strength training.
Pay careful attention to form. Good form is essential for maximum results and for injury prevention. Lower the resistance or do fewer reps if you can't maintain proper alignment or you're using momentum to move the weight.
Get enough rest. The more intensely you train, the more recovery time you need; rest 48 hours between workouts. Overstressing your muscles could slow your progress or, even worse, cause an injury. If you're still sore after a day off, rest another day or two before hitting the weights.
Stop if you feel pain. Your muscles should feel challenged by the final rep, —but you shouldn't feel any pain in your joints.