In theory, fly-fishing is a simple sport: Pick a body of water, choose a fly-fishing rod, select your “fly” (or bait), tie a secure knot, cast your line and, hopefully, land a fish on the other end.

With these expert tips, tricks, and list of must-have gear, you’ll have everything you need to hit the river and cast your very first line. Picture this: Crisp, early-morning air, the sound of a ...