When I go for a jumping session I make sure I choose the right gear. My ideal jumping setup is my 4.2 Hucker with my Roberts custom slalom jumping board. Being overpowered makes jumping easier, so I rig big.
The first rule of jumping high is you have to go fast. To go fast you have to be comfortable and in control.
Once I'm in the water I spot a ramp as far out as I can. I look for a big white water breaking towards me, knowing that the wave behind it will be a good steep ramp. The ramp shouldn't be too far upwind of me, because going upwind kills speed. A steep ramp is better than a big round ramp.
As I enter the trough before the ramp I press the board into the water, building up energy to release at the apex of the ramp. This gives me extra boost. Ideally I'm taking-off of the ramp a millisecond before it breaks to white water. Once in the air I tuck the board up under me and point my toes to expose the windward rail and bottom of the board to the wind. This helps me increase distance.
I constantly trim the sail during my jump to make the most of the wind. I bear off a bit in the air, and look way out ahead for my landing.
If I'm sheeting in the sail properly my jump will feel foaty, and my landing will be soft. I open up my stance a bit for the landing and extend my back leg to come down tail first.