Basically, when you "drip" a drop or two of juice directly onto the atomiser`s heating coil, vape for a while (ie: a few seconds or so) and refresh it by dripping again...and repeat
continually
Onto something like this...a 306 atomiser
it will have a "drip tip" mouthpiece on the end of it of course so you don`t burn your lips off.....
(You could "drip" with anything that has an exposed coil)
I have tried it, it`s useful for testing out new flavours as you don`t need to do much to clean it out afterwards apart from rinse, and doesn`t hold onto flavours for too long,
as for daily use, some people absolutely love it but I personally found it to be the vaping equivalent of lighting a fag, taking a drag, stubbing it out, picking it up and lighting it again -
and going through that whole rigmarole over & over ad nauseam....but there you go ! lol
Some people say the flavour is better than using anything with wadding etc as well as it`s more "direct".