I wanted to give some information that should be common knowlegde but a refresher may not be a bad idea.
Squats-You can injure your back doing squats if you 1) grip the bar unevenly causing a twisting movement when you stand up from the squatting position, 2) stand with your spine rounded (hyperkyphosis) rather than straight, 3) lean so far forward that your knees travel forward over your toes and your heels come off the floor causing you to lose your balance, or 4) hold the bar too high on your neck causing you to lean forward.
Doing squats can damage your knees if you do not squat until your thighs are parallel with the floor or if you squat so quickly that you lose your balance. Also, if you squat too far, you are more likely to trap and damage the meniscus, or tissue that forms a cushion between the upper and lower leg bones at the knee.
Squats are a beneficial technique that an athlete, who has stopped growing, should include in any training program to increase strength and power. However, to prevent the injuries that can occur with this lift, athletes must avoid careless errors in technique.
Lifting behind the neck
Another type of lift that is potentially dangerous involves lifting weights behind your neck. This type of lift can easily injure the shoulder because in this position, too much strain is placed on the ligaments connecting the bones in the front of the shoulder. You can strengthen the trapezium, rear deltoid, and latissimus muscles by doing other exercises that do not place the ligaments at risk of injury. These exercises include shrugs for the trapezium, rear extensions with dumbbells or a straight bar for the posterior deltoid, and upright rows or cable rows for the latissimus muscles.
Although any athlete can be injured while lifting weights, weightlifters can prevent many injuries by using proper positioning and lifting techniques and by using the right exercise to strengthen a specific muscle group.
I was able to find pics of proper and improper form.
