I'd look at other tracks that you have ridden and try to follow what they have done.
Big gap jumps are dangerous. A friend of mine has a gnarly SX style track in his back yard, yet he'd rather come ride on my track, because it's safer and more fun. Leave the big "go or die" jumps to the pros.
One of our local public tracks just changed all but one gap jump to tables. They got tired of watching less experienced riders leave their place in an ambulance.
Otherwise, use clay for your jump faces and berms (not top soil), and experiment.
The steeper the face, the higher you will go, and the more it will hurt if you screw up. About 30 degree angle on the faces of jumps and you should be safe.
It might just be me, but for a good track layout, I'd rather get the line down, then go back later and add obstacles to the track where they need to be, rather than just arbitrarily putting jumps in. Put your jumps in where you need something to slow the rider down.
My track has a nice fast open section, and a tight twisty slow section.. In a couple weeks it'll have a fast scary woods section. Can't wait.
Whatever you end up doing, make your track fun.