In the process of teaching fly casting, certain faults of technique show up regularly among my students. In the notes I send to each student after a lesson, I find myself reiterating certain principles time and again. Here are a few common ones. I hope they’ll stimulate you to think about your own casting.
The length of the casting stroke changes with the length of the line being cast. The rule is this: “Short line, short stroke. Longer line, longer stroke”. Most anglers are unaware of this concept, and consequently can’t turn their fly and leader over with authority. But adjusting your stroke length to the line length is absolutely essential to good casting. It’s how you maintain complete control of your line, leader and fly—regardless of wind.
In a mechanically sound casting stroke, the elbow moves up on the backcast and down on the forward cast. There should be no pushing-and-pulling, parallel-to-the-ground motion with your arm or elbow. Ever. The elbow moves up and down—always. It may be a short up and down motion (as in a short cast), but it’s always present. See video of this here: https://www.youtube.com/watch?v=oEtfIV1pOqk
If you’re tailing your loops or your fly ticks your rod as you cast, your first corrective thought should be to raise and lower your elbow during the stroke. Most people think tailing loops are caused by uneven power application during the cast (shocking the rod). While that is one cause, in my experience it’s not the most common. More loops are tailed because of a failure to raise and lower the elbow. Raising and lowering the elbow (which raises and lowers your rod) creates a clear path along which the line can unroll without hitting the rod or colliding with itself.
If your leader and fly turn over lazily and get blown around in the wind, shorten your stroke. Authoritative turnover of leader and fly is never about equipment, and only rarely about using more effort. Rather, it’s about using the proper length stroke. Most folks will need to shorten their stroke as the first step towards a powerful turnover of their fly. In strong winds you may need to use more effort, but remember that if your stroke isn’t the right length in the first place, no amount of effort will straighten your line and leader.