From your previous posts I'm assuming you are talking archery hunting. Of course the stalking technique is the #1 choice. Go after them in the aspens but that hardly ever works out. Second, if they are bedding in the same ole group of trees then get in the trees while they are out feeding and ambush them as they come in. Third, stay out of the trees but get close enough to ambush them when they come out of the trees. You might sit there for several hours waiting on them to come out, but thats hunting. Or, ambush them when they come out in the evening into thier feeding area. Fourth, so you blew them out and they took off. Watch the direction that they travel to escape. If possible, have somebody watching the area from afar, sometimes a wise ole muley will use the same escape route multiple times. Bingo, get in the escape route and have somebody lightly push them to you. Another thing I forgot to mention is, ambush them at thier water source.
Several years ago while archery hunting I ran into the same problem. Its just tough to get them when they live in the trees and your using archery equipment. What I learned was that I needed to choose more archery friendly hunting areas. Areas with cliffs, rocks, scattered brush instead of stands of aspens. I started finding deer bedded under rocks, in sparse brush and under large over hanging trees. My success immediatley went up while choosing this type of terrain. Also, during the middle of the day I'm not laying around waiting for the bucks to come out of the trees in the evening. I'm lurking around all day long following ridgelines peeking over the top or glassing under every piece of shade I can find. You WILL find bucks using this method in less treed areas. fatrascal.