Learn your wrap around turns.. I am big on pumping down the line.. and very often I end up gaining so much speed, I shoot myself right off the shoulder and out of the wave. hah. So I started making my big wrap around turns to come BACK at the closing wave. You can do that.. OR.. learn to drag a hand in the face or something to slow yourself down. If you are on your backside.. drop down into the "pig-dog" stance and plant your butt in the face to create some drag.
If you hold a straight line down the line.. you'll shoot yourself right out of the pocket (if its a slow moving wave).
Just some thoughts. Start putting more turns and carves into your riding to position yourself more on the face.
Another scenario I've found is that if they are slower waves.. I would take off right if I want to go left.. or take off left if I want to go right. When Im down in San O I do this. Its slower, so I'll take off, head a little inside, then cut back and end up RIGHT on the peak.. If the wave is breaking right.. I take off and head left for a split second, then turn around and fly down the line on a deeper line than out on the shoulder.