A couple things I work with people on...
Don't hammer the throttle off the lip, hold a consistent speed which will keep you more level off takeoff (also hammering through the takeoff pisses off the guy behind you that still wants to hit that jump!) get used to NOT hitting the gas on takeoff, you'll learn quickly how to judge speed better, and you'll learn to carry proper speed instead of compensating at the last minute.
find a ramp that leads to a flat (a small plateau), practice speed control on the run-in, and after you get into the air, tap the brake to level the sled, then hit the gas right before you land.
This type of "simplified stepup" allows you to start small, land with little speed, and learn brake control with little to no consequence.
After that, you can find more of a traditional jump (takeoff & downward landing) and feel comfortable with using your brakes.
Probably didn't explain that stuff worth a crap...
edit, a pic I always liked because it shows the brake/ throttle cycle pretty obviously: