This method starts with your proper position in the river to the feeding/rising fish. Of course your position should be upstream from them and getting to that position without spooking them is half of the challenge. Do this slowly and quietly, being ever vigilant not to disturb the current flow to the fish with your body.
In the diagram (don’t laugh at my drawing) below notice the fisherman’s position upstream from the fish. The current eddies and seams he is creating are flowing to the side of the rising fish. His position will also be important at the end of his drift, but I’ll cover that later.
Unless there is a whole pod of feeding fish together, you should target one individual fish and place your cast so the current will carry your offering to him. Start by casting your fly 5- 10 feet upstream from the active fish. Your fly line should be curvy like a snake when it lands on the water. Do this by stopping/aiming your delivery cast a little bit higher off of the water than normal and pull your rod tip back towards you just a hair right after the line straightens out before falling to the water. Done correctly and you should have a curved line. Especially for faster water, this can be essential to not having an almost immediate drag on your fly.
Next, be prepared to feed out line pretty fast. Too much and too fast is better than not enough and too slow. I feed out line using a side-to-side motion with my rod tip. Move your rod tip to the right a couple of feet and place it in the water. As you move the tip back to the left, let the water drag out some line through the tip. (I call this “shaking out line”.) Do this fast a couple of times and then mend a good curve into the line as it starts to drift. Be sure to stay ahead of the speed that the line is flowing down with the current by shaking line out as much or as fast as is needed. As your fly drifts over the area and there are no takes, let the fly and line continue to drift a few feet below the fish before lifting it for another cast. And this is where I said your position would later come into play.
If your position is slightly to one side or another of the feeding fish, it will help to keep your line from flowing directly downstream over the fish. Also, it can help keep you from scaring them when you pick your line up for another cast, after the drift. Depending on the amount of line you have out, either strip in a little line or go ahead and pick it all up for the next cast. But, before doing this I would recommend holding your rod tip far to your side, forcing your line to drift farther away from the fish’s holding area. Do this as soon as your fly has drifted out of the strike zone, giving the current time to pull it all to the side, away from the fish. This is just another step in trying to not scare the fish. If you have a hookup, try to force the fish to the side and out of the area as quickly as possible, lessening the chance of putting all of the other fish, if any, down, as it thrashes about.
I have found that often fish caught out of a pod of holding fish are more aggressive when taking pupas and/or emergers. I believe there are times when more than one fish is going for your fly and the fastest one wins, resulting in a hard, fast strike. They can just about jerk the rod out of your hand. Break offs are common because of this, either the fish breaks the tippet from hitting so hard or it is the fisherman setting the hook too hard. Truly, in this scenario, if the fisherman sets the hook at all, he will be stressing his terminal tackle, often to the limit. Hard strikes, such as these, only require the fisherman to merely hold on or just simply start raising his rod tip. The fish has already done all of the hook setting.
As Mike B. mentioned in an earlier thread, you can use shock gum or a shock leader to help prevent break offs. When I am having trouble with break offs, I’ll put a length of frog’s hair tippet (it’s pretty stretchy) somewhere in my leader system as I step down tippet sizes to the final size I want to tie my fly to. But, alot of it is still conditioning yourself to judge the take and set the hook accordingly. It has taken me years to be able to do this, but there are still times I can’t get it right and pay the price in lost or missed fish.