A multimeter is a useful device for checking the resistance of coils. There are lots of good ones out there that can “zero out” to enable a good reading, but many of the cheap ones do not have this feature. What does zero out mean? Essentially it is eliminating the resistance of the leads and probes so that you get a good reading. Touching the two probes of an inexpensive multimeter together will likely give you a .4 or .5 ohm reading and this must be compensated for before testing your coil.
A good multimeter will do that compensation for you by zeroing out, while a cheap one often will not. In this case, just remember to touch your leads together first and then subtract that reading from whatever you get when testing your coil. For instance, if you get a reading of .4 with just the leads touching and 1.9 when you test the coil, then you will want to subtract .4 from 1.9. The result is 1.5ohms, which is the resistance of your coil, and that makes for a good vape!