Nzboardlife is right, it's about finding your 'sweet spot'.
For me I usually give a small pop as my board is passing the lip (maybe about halfway passed). Every jump requires a bit of pop (sometimes so little it seems more like a launch) to it and the amount depends on how the feature is set up that day.
Unless you are going into a spin, you will want to hold a reasonably flat base riding into the transition.
A couple of other points...
Take a couple of minutes to watch other riders hit the feature first. This will help you gauge your speed and approach on your first hit.
Pick one point on the lip. Decide on the line you are taking through the jump and follow it all the way through. This isn't something you want to decide as you are coming into the transition (usually resulting in getting bucked).
Gorilla stance. Crouch down and center your weight over your board. Don't ride the transition, ride over it. In other words don't let your weight shift back with the transition, you want to keep the general momentum of your body heading forward. I know that is probably confusing.
Lastly, COMMIT! YOU CAN DO IT!
Last edited by LouG; 09-08-2008 at 02:40 AM.