Time and again I see clients who are, at very least, decent casters bonk fish right on the noggin. One of the biggest reasons (I think) for this is where we focus our eyes. Once a fish is spotted, the anglers recognizes direction of movement, distance, etc. anglers should focus on where the fly should land, not solely the fish.
If their eye is focused on the fish then that's what they're going to hit. Focus on where the fly should land and make the cast! (this is that split second where that couple hours worth of practice before the trip goes a long way).
So, that's fine and dandy, but where in tarnation should one put the fly? Well, as it was put to me a long time ago "you might start by throwing at the end that eats"
After that you might want to get a tad more technical, but not much. To present the fly to Tarpon, Bonefish, Permit, etc., there are a few things I think are a must.
**note: everything here is general, the nuances of migratory Tarpon fishing with regard to angles, etc. is much more complex. We'll save that for another day.
1- I always want the fly in front of the fish. The fish swims into the fly.
2 - wherever possible I want the fly to cross the fishes direction of travel when it is retrieved.
The best way I have found (for me, and others seem to get it as well) to achieve these are to throw at a box, not at the fish.
Always focus, and try to land the fly on the forward, far side corner of that box from the fish. If you do this, and the fly goes where you focus, the fly will be in the perfect spot.
If you focus on the fish, you'll probably hit the fish.
Here are some examples to outline what we're talking about:
Approaching Shot: fly lands forward corner of box, whichever side fish is traveling (fish going left, throw left corner, going right, right corner). **Even if a fish is coming straight at you throw to one side of the box. This will cross the fish with the fly. If you are right handed, throw to the left corner, opposite for left handed caster.
Going Away Shot: You're probably screwed, but you never know. Think of the box ahead and to the side of the fish. The fly should land in the farthest corner of the box from the fish and direction of travel. Drawings show both left to right and right to left scenarios. **If you take this shot, don't move the fly when it lands. Let the fish turn and react to the fly and then retrieve as appropriate. If you strip immediately you will likely spook the fish.
If the fish doesn't react to the fly then you chalk it up to a low percentage shot anyway and move on.