Point the board in a broad reach and clear the sail from the water.
Extend your clew hand so the clew is out and away from tail of the board. Place the heel of your foot on the centerline of the board, between the footstraps.
While extending both arms, stretch your body out toward your clew arm. The emphasis is on the clew arm. At the same time pull the tail of the board toward your buttocks in preparation to mount the board. These are apposing actions: extending with arms and pulling with your back foot.
As the sail pulls you forward then keep extending the clew arm, put the front foot on the board, and mount the board.
You will be pulled out of the water in a beam-reach.
When you are out of the water and relatively stable then flip the sail by letting go of the back hand and pulling the mast-side hand toward your chest. This forces the sail to flip more vertically around the axis of the mast.
Grab the mast below the boom and let go of the other hand for a smooth and controlled sail flip.
Now grab the other side of the boom and remember to keep slight tension (pulling) on the mast so it stays vertical and close to your body.
Position both hands to the boom and adjust your feet as crescendo to a wonderful waterstart