Three and one half inch, Countdown Rapalas are deadly on the Green River for big browns and an occasional rainbow. Cast the Rapala up and across a deep run. As the lure begins to sink and move downstream, begin the retrieve.
Use a jigging motion. Pull up on the rod and then drop it back down while reeling in the slack line. The Rapala will drop back and begin to move downstream. About 90% of the time the trout will hit the lure as it is dropping back. Watch the line intently for any unusual movement and set the hook if you see any. Generally you won't feel the trout hit and if you do, it will only be a light tap.
Cast to the head or foot of deep pool and begin a slow retrieve as described above. Many of the pools on the Green are 15 to 20 feet deep and the big browns are right on the bottom. Jig the Rapala so it dives deeply and swims within a foot or two of the bottom for best success.