Uphill tips
1) The first section is the steepest - don't go out too hard!
2) Taking "baby steps" will help you maintain a good cadence. It's like switching to granny gear on a mountain bike.
3) On long, steady hills, switching often between walking and running is tempting, but it makes you lose momentum and cadence. Pick one or the other and go with it. Switch only when the terrain switches.
4) Posture is everything. Leaning forward from the hips puts too much pressure on your back, an erect posture will provide a better push-off.
5) Look uphill, not at your feet. This will allow you to pick the best line and free up your airway.
Downhill tips
1) Don't over-stride, each landing will put extreme stress on your legs.
2) Lean forward not backward keeping your whole body perpendicular to the ground. Again, this will save your quads and allow you to run faster.
3) If you need to control your speed cut your stride length and increase your cadence. Like using low gear in a car.
4) Like a hurdler, step over, not on rocks and other obstacles. Keep your body level and lift your legs.
5) Pick as straight a line as possible down the hill. The more you move left and right, the more you stress your legs and increase the distance.