In my exercise classes, I notice a lot of people doing an improper bicep curl. My belief is that if I am going to invest the time and energy into exercising, I want to make sure I am getting the maximum benefit. Proper form, to me, is the key to exercise and hopefully it will also prevent injuries.
When you do a bicep curl, you want to make sure you are focusing on isolating the bicep for maximum benefit. It is important to keep the elbows in your sides. And, as you lift the weight, make sure your elbows point down and not forward. When your elbows point forward and spread away from the torso, you start to incorporate the deltoids (shoulder muscles) in the lift and take away from the bicep benefit. Also, because the deltoids are being unintentionally used, you risk the possibility of straining the deltoids (especially the frontal deltoids). Check out this video for a good visual example.
Here is a video I made with a few gym members to demonstrate what I see and what I would prefer to see.
