There is only four hard and fast rules for choosing a fly.
First, take the time to really study the water to determine what is either swimming about under the water or is hatching off the water.
Second, if you see feeding fish, tie on an imitation that mimics the most likely food source. Third, if you don’t see any feeding activity, try an attractor that suggests an insect or baitfish common to the area.
Lastly, and this is an important point, pick a fly that inspires your confidence. You’ll fish it with more focus and intensity, which almost always turns into better luck at the end of the day.
Of course there are too many times when a fly that should have worked doesn’t, or when you can see fish feeding but you’ll be damned if you can figure out what they’re eating.
This is no big deal. If you caught every fish in your immediate vicinity, you’d be bored out of your mind in an hour or two. So for whatever it’s worth, enjoy the days fishing and the ones you catch, don’t worry about the ones you don’t, as they always say "there's always tomorrow".
What’s unique about fly fishing flies is that they can be designed to mimic an insect at different stages in the creature’s life, starting with a single egg, to the emerging nymph, to the airborne adult occasionally alighting on the surface of the water.
The mayfly is a great species for the beginner to fly fishing to imitate because one can fish three different versions, nymph, dry, and wet, depending on the phase of the hatch during the hatching period, which won’t be obvious unless you see plenty of mayflies landing or taking off from the water.
While casting dry flies might be to some fly fishermen/women the best form of the sport/art, and for many, the most exciting, trout actually get more of their food beneath the surface.
There are a handful of key flies or “patterns” that should be at the forefront of any advice on fly fishing basics.
The top dry flies include Adams, Dave’s hopper, black midge, bivisible and the royal coachman.
Wet flies: Black or brown woolly worm sized from 10-12, black ant, and you can’t go wrong with large to mid-sized stimulators for brown trout.
To mimic small minnows you’ll want to have an arsenal of streamers in both natural earth tones, as well as flashy bright colors.
Also try sinking nymph and emerging patterns.
You’ll want to have a variety of wet and dry flies, along with some nymphs and streamers wherever you fish. And it’s a good thing to have at least six of each because before you know it you’ll be down to the last one when you realize that's what the bigger fish are eating.
A great option for a beginner or experienced angler is a dry fly with a short white “parachute” of deer hair sticking up from the insect’s thorax area. It makes a brown or tan fly much more visible, yet fish can’t see the white hairs from below. Parachute-style presentations have become more popular recently.