Fly Fishing For You

it depends on what you are fishing for but if i was fishing for trout i would start with a streamer

References :

the fly is not as important as the technique for tying on the fly, use a 2lb leader and a blood knot, practically invisible. this will catch more fish for you.I like the nat or the coachman fly. I prefer smallest flies. good luck
References :
roaring river, cassville, mo. fisherman

Thats a tough question. The "perfect" fly at any given time or circumstance will change according to conditions, time of day, time of year, water clarity, barometer, temperature.

If you start hooking fish regularly with a particular fly, bingo, theres your "perfect fly" for the moment. It will change. Now you must become the "perfect" fly angler and adapt your fly, or your pesentation to what they want now.

It's an ever-changing, ever-adapting circle to achieve the "perfection" you seek. You do it and you don't even recognize it. The big bend in your fly rod is a good indication that you have arrived.
Good Luck!!
References :

There really isn’t a perfect pattern that will do it all. You’ll have to match the hatch when it comes to fly selection. Once you selected the pattern and size, you’ll probably still have to select the best color for the water.

However, there’re a couple of patterns that work excellent for me in many waters on many species. For freshwater, a wooly bugger would really stand out. I’ve consistently caught trout, carp, large mouth, small mouth, crappie and larger bluegills on wooly buggers. I don’t fly fish at night too often but I highly suspect a black wooly bugger could land me a catfish if I really tried. For saltwater, a deceiver fly is a good all around choice. Most if not all predatory saltwater fish would hit a deceiver fly. A deceiver will work in freshwater as well.
References :

I have to agree with James.

If there WAS a "perfect fly", my vote is with the Wooly Bugger.

A black Wooly Bugger can catch a WIDE variety of freshwater fish.

For saltwater flyfishing?

Clouser Minnow.

(Thumbs up to Kevin & James.)
References :

lol, NO! although there are loads of fly anglers out there who wish there was! lol, the great thing about fly fishing is the fact that its constantly changing, fish will take one fly all day long, then ive gone back the next day with the same setup and not had a single take. There are many multi purpose flies, although they dont always work. One of my favorite flies to try in new waters is the hares ear, especially the gold ribbed hares ear, damsels also work very well fished subsurface, witha olive marabou tail, with some krystal flash added to it. Fluorocarbon can greatly increase youre takes, i recommend airflo g3, or riverage fluorocarbon.
References :

I really like the PTN (pheasant tail nymph) it represents loads of things, also the san juan blood worm is pretty good fly, along with orange spot czech nymphs.
References :

maybe a wooly bugger but here is a list of the best flies in fly fishing

http://www.associatedcontent.com/article/995704/the_best_flies_to_use_when_fly_fishing.html
References :
http://www.associatedcontent.com/article/995704/the_best_flies_to_use_when_fly_fishing.html

The short answer is “no.” There are just too many variables, ranging from what you are fishing for, to the kind of water, to ambient conditions, to what the fish are feeding on.

However, the wooly bugger, and all it’s variations, comes close to being a universal fly. It can be fished as a nymph; as a streamer; as a struggling baitfish or terrestrial. It’s versatile enough to be worked anywhere in the water column.

Basically, it just looks alive and edible.
References :
http://www.the-outdoor-sports-advisor.com/fly-fishing-basics.html