This is a question that gets asked a lot!
This is not a simple question as there are a lot of different methods and opinions on atty cleaning. So, I asked the question in the NV forum and here are a few responses I got:
To thoroughly clean an atomizer I submerge it in Everclear Grain Alcohol, agitate for a couple of minutes, drain the alcohol out of the atty and repeat this process a couple of times. I also have an ultrasonic jewelry cleaner that I use for agitating the atties but this is not necessary.
Rinse atties in hot water and sit on paper towels with the battery connection facing up and allow to dry overnight.
My new favorite way of doing it is with a large syringe, a short piece of tubing that fits on the syringe and into a drip tip. I just suck the alcohol in and out a few times, blow it out and dry fire it 3 times holding the power for 3 seconds. Remember, if the coil is all gunked up, flushing and cleaning will have no effect.
I soak mine in pure grain alcohol a few times then blow it out, i do not let it dry then i add a 50/50 VG/PG mix so the wick don’t dry out and store or use it. I also blow the old juice out once a day this helps with flavor.
I’ve started blowing my out in to paper towel once a week, and it seams to work well.