New coil builder here-- so far I've tried:
A 28g 1/16" 13 turn tight coil @ 1.4 ohms, oriented about 20 degrees clockwise of the post screws, wicked with cotton. Lots of vapor and throat hit but the flavor of my usual juice was odd, different. Coil was centered over the air hole and tried at 1mm and 2mm heights.
A 30g 3/32" 8 turn coil that came out at 2.1 ohms. The turns are widely separated and the coil is about 2mm above the air hole. Again, wicked with cotton. Vapor production and throat hit are so-so. Flavor is more to my taste on this one-- this juice I've been using for a couple of years tastes more intense with this setup, even though I've diluted it with PG to 60% concentration [amazing!]. Problem is, the coil tends to pop juice toward the end of the hit so I have to take primer hits occaisionally. I'll try squeezing the coils closer together when I rewick it tonight.
I've been using Koh-Gen-Do cotton and love it because of the parallel fibers and clean taste. It's very easy to adjust the thickness while pulling it through the coil... if it's too tight, just grab the tweezers and pull off a few fibers from the side, then try pulling it through again.
I got them here:
Koh Gen Do Organic Cotton Pads at DermStore
One last comment: these post screws suck! They're not flat on the underside and the wire slides out from underneath as the screw is tightened. I found some M1.6 SS screws at McMaster-Carr to try, and think I'll also look for some tiny washers for just-in-case.