The key to being a good free throw shooter is practice, practice, practice. If you shoot a couple hundred from the charity stripe on a daily basis, you'll get better - it's inevitable.
But there's something to be said for natural ability. All the practice in the world won't help if you're coming from the Shaquille O'Neal school of free throw shooting. Actually, it's a game between Western Carolina University and Appalachian State. Behold, possibly the worst free throw attempt in the history of organized (definitely televised) basketball.