Let me preface this blog by saying I am a fisherman, who loves to cast. I am not a caster, who loves to fish. I began casting in my teens with no formal instruction. Then, the cast was just a means of delivering the fly. Now, I find great pleasure in not only the fishing, but also the casting. I highly suggest reading Joan Wulff's Dynamics of Fly Casting for a detailed and succinct analysis of the physics of casting. She is a great mentor of mine and I don't believe anybody does a more thorough job of analyzing the cast than her.
The first question I am usually asked by a student in a saltwater school is how far should I be able to cast?. There are a few answers to that question. For sight fishing in the salt, superstar casts are not necessary. An angler should be able to accurately cast 50-60 feet IN EVERY DIRECTION. This means against the wind, with the wind and with the wind blowing across either shoulder. Learn to work with the wind. Believe it or not, it is your friend. When it is howling, you can get much closer to the fish and they are far less wary than they would be given calm conditions. Generally, the angler does not benefit from making excessively long casts when sight fishing, because it is harder to discern the reactions of a fish at great distances. That is not to say that a "hail mary" shot won't catch you a fish, but the ability to see and respond to the fish's movements will enable you to fish the fly more effectively.
Conversely, long casts are advantageous in situations that require the angler to prospect for fish or "blind cast". For instance, striper fisherman cast extremely long distances. These casts enable them to cover water, attracting the fish into their zone and ultimately to their fly. An angler also use distance casts to help sink a fly. Heavily weighted shooting heads can descend to depths of 60 feet or more with distance and a waiting period. Although this can be an arduous task, it is effective when fish are deeper in the water column.
The following are a few things I think about when airing out my fly line:
1). No slack. Keep your rod tip down and make certain that your fly line is free of slack before you begin your cast. If there are wiggles, zigs or zags in your fly line, most of your initial stroke will be simply removing slack. You will not be loading the rod.
2). Use a smooth, strong acceleration all the way to the stop. Decelerating will reduce line speed and result in a loop that is neither tight nor aerodynamic.
3.) Keep it tight. The rod tip must travel or track in a straight line. This also tightens up the loop.
4). No creeping. Don't try to rush your forward cast. Wait for your back cast to unroll completely before you initiate the forward stroke. Think about dragging your rod and fly line through the air instead of punching the rod tip.
5). Pay attention to your grip. To drive that last cast, give the cork an extra firm squeeze.
6). Shorten it up. If your casting is off, reel in some line and make shorter casts with better loops. Also, try not to carry too much line in the air.
Again, these are tips that have helped me improve my distance casting. I suggest a 7 or 8 weight rod for beginners. Sometimes it helps me to work on one element of the cast repeatedly. If you start to feel fatigued or if you feel you are slipping back into old habits, stop and come back to it later. Lastly, enjoy the process. While goals are essential, it is important to take pleasure in the practicing and, ultimately, the casting. Go launch one today!