Wooly Buggers (black and Olive) Black Stone Fly and White streamers on larger flies. Tiny BWO's maybe 18-22 or even smaller for afternoons when it starts to warm up a bit. Don't forget small haresear and prince nymphs may be needed also. Tiny midge larvea like a blood worm and even some Y2ks. Egg patterns work, if you don't think it's cheating!
One tip is to dead drift the buggers and streamers as normal, but when they swing around, let them sit at the end of a run for a minute or so. Many times a fish will try to move it out of its area by picking it up much like a bass would. The strike may feel more like a little tug than a tap. Keep a little line in your hand, a foot or so, and when you feel the "tug" release the slack and lower your rod. The fish is turning down stream to either drop it out of its area, or is going to eat it. When the line comes a little taunt, pull slowly and sideways to get a hook set. Sometimes it works sometimes it doesn't! Buy hey, it's fishing! Oh, and unless the water is stained from rain and run off, 6X tippet is the very largest you might want to use. I would probably even have 7X and 8X on hand just in case. Flourocarbon will be a big help there too! GOOD LUCK!!!!