The last factory made coil I used was on an eGo! It's been a few years. They were hard to prime and we used all sorts of methods to make them absorb
juice. The best way was to fill the "condom" rubber cover with juice and slowly insert the coil back into it, threads down (as Baditude posted). Wait a few minutes until the top showed juice in the cotton, let the excess drip off, wipe it, and vape.