Using the Right Hook Size
Whatever size of fly you are making, you will need to use the proper size of hook. If you are tying a fly that is an attempt to mimic a leech or other underwater animal, you can use a larger hook than if you are trying to tie a fly that simulates a salmon egg. Also, you will want to use the right size hook for the type of fish you intend to catch with your fly. It would be foolish to use a very small hook to try to catch a large fish, so selecting the proper hook size is an important fly-tying technique.
Wrapping the Fly
Another fly-tying technique that you will have to master is wrapping the fly properly. This involves using string on a bobbin, much like a sewing machine. Wrap the fly securely enough that the material does not come loose or fall off the hook in the water, but not so tightly that the shape or overall look of the fly is distorted to the point that you cannot tell what it is supposed to be.
Using Colors
Using different colors of feathers or material is a way to make flies visually interesting to different types of fish. Using these colors, you can attract different fish to your lures. This is a technique that you can learn over time from experience by seeing what colors work best with the fish in the areas where you are located, or by reading books about fly fishing.
Learning Your Insects
Learning the different types of insects that live in rivers, versus the types of insects that live in lakes, is an important technique to learn. If you are trying to use river flies in a lake, you will not be reaching the right type of fish that you are trying to catch, because these fish will be unfamiliar with the bait that you are offering up.