Lot's of fun tricks to handle challenges like these. We'll cover them in two mornings of free training at the Gypsy Tour, Oark, AR July 16-17. And you get points for attending (10 points total, 5 for each day).
Here's a sample: when crossing roots or trees on a sidehill trail anticipate the tires sliding downslope. Either change your angle of approach or look for a downslope branch/knot to hold the wheel. Keep the front wheel light or wheelie over as you cross so it's less likely to slip but chop the throttle IMMEDIATELY after the front wheel clears. Then smoothly get back on the power AFTER the rear wheel crosses. To make this crossing you will need a little momentum.
This technique is pretty to learn and practice. We start in first gear over a small pole on flat ground.
We'll also cover two-track and ruts, slow speed and fast, and of course your favorite and mine, sand and gravel...
See you there,