Look at both the Kidderminster & RHR tracks...and use ideas from them! Best 2 tracks in the country for features IMO.
Go down as well as up if drainage can be sorted out.
Keep the features/technical sections close to the rostrum, and in good line of sight...much better visibility where you need it most...keep the farthest corners as easy sections.
Make sure jumps have good long down ramps...little ups and little downs are rubbish to race on!
Go for shapes and undulations and smooth transitions as much as anything...jumps are cool if they are done right, but aren't the be all and end all. Well placed shapes can be used as ups, downs, off camber sections, mini banked corners if the track is laid well over them.
Maybe try to exagerate any natural features you might already have.
Good luck guys and nice work so far...looking forward to seeing it soon