If you're new to pull ups here's a quick review:
1. With an over hand grip, grab the pull up bar.
2. Keep your abs tight and try to imagine pulling the bar down to you versus you up to the bar.
3. Squeeze the shoulder blades as you raise yourself up.
4. Return to starting position.
When you're doing pull ups, not only do you need to have a pretty strong hand grip (you are afterall pulling your whole body weight up with just your hands), you also should be wearing some sort of weight lifting grip pads
You'll find that you if you don't have to worry about your hands slipping off the bar, you can actually get a better workout!
