As for gear, use filters and EQs, so when particular bands of frequencies stars to clash you can start carving. Don't be afraid of cutting low end, nor high ends. Let pass only what is "beautiful", instead of boosting.
-- dadodetres
Thanks for the wonderful advice. In fact I was wondering about filters use in drones, most of the time the talk seems to be about oscillators and tuning, which I get is the most important part for drones, but not that much about filters. In fact, I've been trying out some of the techniques proposed so far and I'm enjoying a lot using the LR4 Crossover, I just send each output to different parts of the system and turning a knob introduces interesting changes.
Still not speaking drone, but many good ideas in this thread and lots of inspiration.