Proper Hang

BELOW TREE-LINE
What if there aren't any trees nearby?
Do you recommend tying a figure 8 knot above the slider when the bag is cinched?
Or only on the lengths going around the branch?
Tie a single overhand knot (like the knot you use to tie your shoelace before making a loop) above the slider, then take the long loose ends and tie them in a figure 8 around a tree branch. The overhand knot is just extra protection in case there is a lot of slack in the cord and the bear wants to try to slip open the cordlock.
We recommend a figure 8 knot around the branch because it is easy to untie even after Ursack has been pulled on by a 500 pound bear.

ABOVE TREE-LINE
What if there aren't any trees nearby?
If possible, use a rock-climbing aid wedged into a crack high up on a rock, then tie URSACK to the aid.
Since bears can't climb rocks, this should be very effective.
Otherwise, tie URSACK to any object that is too heavy for a bear to drag away. ..