I only started boarding a few weeks ago and had a LOT of trouble getting up too... I feel your pain / frustration! Then I spent a whole week in the water and finally found out what I was doing wrong. Maybe it will help you out:
1) Like Bill said, start in a crouched position, but don't bend your legs too much; If the driver accelerates too fast, the water resistance stop your board and you'll end up hurting you hip ligament... (happened to me!)
2) When you start to feel the pull, lift your hands out of the water, until your arms are out and straight...
3) When your shoulders are out of the water and that the board starts dragging water, point your toes forward and pull yourself up. Let the boat pull you up, and then bring the handle to you.
4) When you are 1/2 way out, just turn the board.
I hope this helps! Maybe I have a totally wrong way of getting out, but it works for me!! You can even get the driver to drag you in the water for a while and you'll get a feel of what works for you and what doesn't... I had soar forearms and blisters for a while because I was keeping my back straight during the whole process. I'd fail at least 5 times before getting up!! ... be patient.