Best advice I can offer outside of all the posted ideas pertains to the insects and the stage of their life cycle you are trying to imitate. Success nymphing relates directly to how you are presenting a nymph and if that presentation relates to the same stage of the natural. For example, if a rise tells you the fish is taking emergers instead of dries fish an emerger pattern (RS2) with a slight strip back during the drift to mimick the rising natural.
The more education on insect life cycles you have the better you will become, in regards, to all fly fishing but especially nymphing.
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