You want to start with deciding what you want in your run/s. Things like the run in from the start, is it on a hill or will you need space to ride in, always give yourself more than you need so if you increase size you still have space. Do you want a straight line or hips. Berms, rollers, step ups, step downs, etc.
Vary jumps, dont start huge either the first few should just be there to get into rythm.
Think big about drainage, the worst thing is water inbetween jumps, so dig inbetween a small amount with an escape route for water.
Trick jumps or gaps or both? Short steep jumps are hard to perfect but big gaps take time to work out distance you dont want to be over or under shooting.
Dont try and build tables unless you have alot of manpower/time. If your worried about testing them just get a door or something for the gap.
Try and use a pit for the dirt rather than random areas saves you losing space if you expand. And wheel barrows and water supplies help massively too.
All I can think of really but yeah hope it helps a little.
EDIT: I just looked at the picture its not a massive place so my reply might be a bit ott. Also see what the grounds like to build with first, some dirt is far to crumbly.