Wherever you're fishing, try to find a local fly shop for intel about what patterns are working and where. Even hire a guide for the day to really get to know the river. But regardless, don't stress out about trying to exactly match your fly to whatever's on the water. "Trout are not the selective eaters we think they are," Rosenbauer says. "I know this from pumping stomachs. Every time I analyze a fish's stomach, I find all kinds of junk. Like different insects of all stages — nymphs, dries, beetles, little freshwater shrimp. Trout are opportunists. As long as the fly is in the ballpark and looks edible, they're going to eat it." A good range of five flies to always have on hand are a black woolly bugger, hare's ear nymph, pheasant tail nymph, a parachute Adams dry, and a stimulator dry. The woolly bugger should be a size 8 and the rest in the 12 to 16 range. Buy a range of flies from the closest shop to your river.