It’s a bit of a long & complicated subject, so I’d highly recommend trying to get your hands on a copy of a book called “JOHN BAILEY’S COMPLETE GUIDE TO FLY FISHING” (which is a REALLY good book).
Here’s the ISBN numbers to help you find it on Amazon
but the general gist of how to go about it.
1) get all your gear together:
– Rod, Reel + Flyline…. usually a set-up with an AFTM weight rating of 5-6 or 6-7 will see you good for most types of freshwater fly fishing.
– Leader material…. personally I just use ordinary monofilament, instead of some of the more fancy ones. This is used to attach the fly to your fly line (which is too thick to pass through the eye of the hook, hence the need for leader material).
– Forceps…. used for unhooking fish with
– Priest…. if you intend to take fish home to eat (such as a trout), this is used to HUMANELY clonk it on the head, and put it out of it’s misery.
– Cap + polarised sunglasses…. essential largely for personal safety reasons (it’s better to accidently hook them when casting than it would be to hook your unprotected eyeballs, for example)….. they have the added benefit of reducing glare from the water and give you a better chance of spotting things under the surface.
– a selection of flies… these are used for bait, and are basically hooks that have been tarted up with various materials to make it resemble an insect of some description. The 2 main types (of which there are more varitions than you’d believe was humanly possible) are “Wet flies” which are fished under the surface of the water, and “dry flies” which are fished on the surface of the water.
– A couple of fly boxes…. basically used to safely store the flies you aren’t using inside your pocket or tackle box. Mine have foam inserts inside so you can neatly arrange them with the pointy bit of the hook stuck into them so you can easily see what you’ve got available without stabbing yourself in the fingers. I keep mine in 2 seperate boxes… one for wet flies, the other for dries (as otherwise I can never remember which are which)..
Step 2 is learning to cast….. the age old method is to practise in a field or your back garden (if it’s big enough)… at this stage you only need to set up the rod, reel + fly line… as these where all the casting weight is, and you don’t really need to bother with the leader + flies until you’re actually out fishing. Passers-by may think you might have escaped from the local mental hospital when they see you practising this way, but it does work.
One main thing to know when you first try fly casting is “never wear clothes with drawcords on them”, because unlike other forms of fishing, your flyline when you are casting & retrieving it is usually dangling round your feet (instead of being reeled tight back onto the reel)…. and as a result you usually end up getting the drawcords tangled up with your flyfishing line (which usually results in some rather colourful language while trying to untangle it all).
The other thing you should be on your guard for, is I found the flyline usually falls back down through the rod rings / line guides (whatever you prefer to call them) the first few times you try it.
To start off casting, grip the handle of the rod in your right hand (or in your left if left handed), then pull enough line off the reel until it’s about down to your knees… then with the thumb & forefinger of your left hand, grip hold of the line so the bit nearest the first rod ring / line guide is tight (and the bit nearest the reel is hanging down)…. flick the rod up, so the end of the line is behind you, then you got to start flicking it back and forth to build some casting energy into the rod (it’s a bit like hammering in a nail with a hammer)……. then eventually on a forward thrust (timing is critical) release the line from between your fingers and it should get the line out.
It’s actually a little more complicated than that, and better explained in the book I suggested. Most experts liken the stages of positioning the rod during casting to the face of a clock (e.g. 12 O’Clock = rod pointing straight up, etc).
Once you’ve figured out how to flycast, and get some distance, the next stage is trying to work on doing it with some accuracy (I usually try to pick a target, and cast to it).
After that (usually achievable with a couple of hours practise), it’s usually best to book a couple of sessions with a flycasting instructor to go from being able to do the basic idea of doing it, to actually being good at it.
Step3… is when you actually get out fishing. It’s probably best to start off at an artifically stocked lake / reservoir rather than a wild river, and to take only the bare essentials as when fly fishing you usually have to be prepared to stay mobile and go looking for the fish, rather than casting at a random piece of water, hoping a fish comes to you…. it also gives you chance to see what insects are flying around near the water, to give you an idea of what the fish are feeding on, so you can try find a good match among your selection of flies.
After that it’s fairly straight forward…….. just try stick to a 1 fly set-up, rather than try to be clever with a 2 – 3 fly set up until you’ve got the hang of it (otherwise you stand more chance of getting in a tangle) + also take a good look around before starting to cast to make sure you ain’t gonna take someone out with your fly if you make a balls-up.
(based on a reply I gave on YAHOO Answers, after I succumbed to boredom and give the dump one last strike before it’s out).