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.

This would be a rod and a reel spooled with backing and line. They start at about $50. If you don’t buy a combo, or if you do, there are some things to consider. First is rod length. I’d advise nine ...