Also, be patient and set the level quiet. Drone is really "powerful" as its moving energy constantly, and magic starts happening after a while, dont fatigue your consciousness, and use it as a life enhancer that can be done for long periods of time.
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.
The base tone is the 1rst and most important decision for a patch, since changing it shifts the state that the drone archives.
2 Oscillators ar "minimum" (not really), one for the base, and a 2nd one for color. which can be tuned to 1 octave highers, or a 5th, or a mayor/mir 3rd or whatever you like. My favourite is to tune the 2nd oscillator to a major 11th higher, which is a major 3rds but 1 octave higher.
Filter those oscillators until you find a sweetspot.
Then Modulate: slow modulation for movement you can hear. Slower kodulaton for "structure" so that the sound travels through many states and the drone does not become boring after a short time.
If the filter movements reduce of amplify the perceived level, accompany them by the same LFO modulating the level so it remain "even". The best drone is always changing in quality but remaining almost "flat" in the amount of energy.
Use attenuators everywhere to archive the sweet spot.
Reverbs are key, but use them wisely. All reverbs have a "decay" limit in which they start to "self oscillate" or become "infinite". Look for that sweet spot which tends to be just a little before that and then fine tune it to the sounds that is happening in the moment. Twik all the knobs in the reverb until you found the sweet spot. Don't go above that because the drone will be taken over ry the reverb´s feedback. (delays may be similar)
Once you have something you enjoy, leave it on and go do some other activity in the house while you hear the drone, it "should" enhance those activities, you can hear is passively, but you may hear things to keep micro tunning the system.
Once the drone is done, consider adding other sounds on top: Melodys (generative or pre programmed) sound "FX" (waves, wind, etc) or anything you like. Make this extras enter and leave gradually with really slow LFO`s if they are on for a lot of time, the whole sound can become too intrusive, make the drone be alone for the most, and have everything else be sparse.
I will repeat this: don't be afraid to filter a lot, more than what you are supposed to. Mix for what you are hearing and feeling in the moment.