A couple of learning hints that others haven't mentioned yet...
1) the tip should go through the CB to the cloth...not a stabbing motion. Imagine the tip penetrating the top of the CB, and coming out the back side.
2) angle the jump cue, based on how close you are to the OB to be jumped...the closer you are, the steeper the angle. The CB will leave the table at the same angle it goes into the table.
3) keep your elbow (grip hand) in close to your body. This works well for underhand jumping, or dart style.
4) keep a very loose grip. It's the lightness of the jumpcue that allows it to 'get out of the way'. A tight grip will not aid in jumping.
Hope this helps...
Scott Lee
www.poolknowledge.com