In reply to LeonardRock:
re you set-up, there is a lot of personal preference involved!
I would either put slings round each tree to a screwgate each then cloves hitch the rope to the screwgates, or, for less kit, just wrap the rope by a few loops round each tree then cloves hitch it to itself. More adjustable than rethreaded figures of 8 too.
Then for a TR rig, at the cliff edge I'd hold the 2 sides the of the V of rope together and put an overhand knot in, which will lie above the cliff edge then a second that will lie below. That way you've got 2 independent strands of rope going over the edge. These should be protected with a rope protector so they don't grate away on the edge.
You can also tie those 2 overhand knots so the 2 strands of rope in between are very very slightly different lengths. That way if any grating on the lip does occur it's likely to affect 1 strand more than the other rather than risk both going through at the same instant.