- crouch with a wide stance for stability
- move your weight as forward as possible both to help the board drop as quickly as possible to avoid being hung in the lip, and use the whole rail to avoid spinning out. Plus falls will be safer, you want to avoid falling to the rear of the board and the lip pushing you on the pointy bits (tail, fins). Or staying in the middle and having the board flipped under you, and getting bruised by the rail.
Look at how surfers go for the tube on takeoffs:

Note that on a very steep face, your feet may not seem very far forward on the board, but your body weight will actually be nearly at the vertical of the nose: