Make sure the site is good: plenty of room for an inrun, sufficient space for a jump with plenty of space for a reasonable transition, and a good, STEEP landing (depending on the jump at least).
Have plenty of people, and even still, be prepared to spend a lot of fucking time building it for it to be "perfect." A lot of people skimp on this, getting impatient after like an hour or some lame shit, and as a result, their jumps are pretty mediocre. Those fresh booters you might see in movies take a good long while to build. Really keep that in mind.
Utilize the more compressed and solid layers deeper down for blocks and shit. You can use skis/boards to create a fence like thing as a frame for the jump. It kind of works, but if you want it to be large and stuff, it isn't very sufficient at times.
Make sure you analyze it well; far too often, the jump looks great up close while you're building it, but if you step back enough or something, the jump might resemble a wall or something. It should be pretty smooth, rather than downward inrun to upward kick.
Spend plenty of time on a good inrun if you want the jump to be worthy of a myriad of tricks and goodness.
Pack it down extremely well, because if it breaks, its a real big hassle to try to fix it.
Have fun with it