I've only recently discovered the joys of dry-dropper rigs, being primarily a nymph angler, and I struggled to get small nymphs on the dropper, which have a tendency to float, to reliably submerge themselves.
Traditional weights, say beads or a wrap of wire or a split shot, are over powered even in their smallest form and would eventually sink the dry fly. The best thing seemed to be a small piece of tungsten sink putty. But the next problem was how to keep the tungsten putty in place. On a leader, I can usually mash it around a tippet knot and it doesn't slip. However, on the dropper tippet, there's no knot.
Thus, Painfully Obvious Tip™ #2:
If you don't have a knot, make a knot.Yes, I see your mind is reeling from the enormity of the task. Let me further elucidate.
Tie the dropper tippet with two pieces of tippet, one twice as long as the other. Use a Double Surgeons Knot to connect the two and tie the fly on the end closer to the knot (i.e. the shorter side). Apply the appropriate amount of sink putty to the Double Surgeons Knot.It's ground breaking thinking such as this that continues to up my game and make you weep with the rage that can only be borne by insane jealousy.
This may work better as a video series. Or DVDs.