It is a technical fishery. Small dry flies are the rule this time of year. Size 20-22 PMDs and baetis. Chucking streamers in the evening right at dark is a great way to bring some of those really big boys to hand.
Don't fish blind, work slow and cast to rising feeding fish. Get a good first drift and you should catch a few. Remember the first cast is absolutely the most important, don't get anxious.