I tie the dropper to the bend of the attractor hook with an improved clinch. The attractor is usually a super bouyant fly like a humpty or wulff. My droppper is always smaller and usually a GRHE #16 beadhead. The trick for me is to use a 1x thinner diameter for the dropper tippet, this allows it to turn over more smoothly. I almost never have "pile-up" problems. Also, I cast the rig upstream, let the dropper sink some, and then, especially if I see fish flashing around, gently left the lead fly. The rising nymph quite often triggers a hard strike.
Cheers
Coughlin