I've had some success, but also far from being en expert. However, starting deep and shallowing up if necessary is best I think. The nymph is not supposed to "hang" under the dry really anyway, its supposed to run through like a nymph, reaching the end of the run and being lifted out before it gets to "hanging" under the dry - ie the dry is acting as an indicator rather than a float. No hard and fast rules though, if they want it hung a short way under the dry as a float, fine, do that. Hopefully the dry will get fish too. For what its worth, the first time I tried this method I already had a dropper set up so just tied the top dry onto that for speed. It worked fine, very well in fact, plus it keeps the dry hook bend free of obstruction for hooking purposes and I did get a lot of fish on the dry too, so I quite like the dropper method. The other way I've been told about which also keeps the top dry free of obstruction is to tie the top dry on, then tie the nymph section on to the line above the dry fly and slide it down til it buts up against the dry fly eye. Almost like tying the nymph off the eye of the top dry rather than the bend.

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