Since I don't have a rangefinder, and all my stands arte pre-hung and fixed pre-season I set my pins at the number of paces, most of my stands are 15-25paces from my stands. I set a 15pace pin and a 25pace pin. As for practicing distances F&S just printed a good exersize. Set up as many targets as you can at varying distances. Using one arrow only walk your course and shoot at each target only once, when you get the routine down,mix up the targets and do it again. Dont re-take a shot until the next time around.
Another method of practicing from elevated stands is to throw some old tennis balls out and try to hit them
These methods will get you used to judging distances very well.