So, a mt bike trail? First define users. Mt bikers of course. Multi use? Dog walkers, horses, kids with parents? What kind of land do you have to work with? Connect with other trails? Any vernal pools, streams, historical, or sensitive areas to deal with? Abutting neighbors? I would highly recommend the 2 trail books put out by IMBA, will answer many of your questions. Bigger questions. Budget, users, who will build it, maintenance?