You might also get a copy of Denny Rickards book "Stillwater Presentation", it is loaded with great stillwater techniques; however Denny has told me he doesn't like fishing deep lakes.
www.flyfishstillwaters.com - Fly Fish Stillwaters
You haven't mentioned how you are fishing this lake, are you fishing from shore or do you have a float tube or pontoon or some other type of boat? Also do you have access to a sonar unit (they can be invaluable at finding structure)? One technique I would use if you have access to a boat/float tube is to target the shoreline shallows when the light is very low (early mornings, early evenings), position yourself within casting distance to the shore, cast into the shore, strip the line back and move the boat a few feet and repeat until you start hitting fish. Also, does the lake have any areas in the summer with good weed growth? If so the bugs will be there in the weeds and you will find fish cruising the edges.