As a general rule of thumb I try and keep my heat flux reading near 200.
For
28g wire I never build lower than 1 ohm, usually around 1.2 - 1.5 ohms, at 15W it provides a nice vape.
For
26g wire I usually build in the 0.8 ohm range and at 20 to 25W it provides a nice vape.
For
24g wire I usually build dual coils in the 0.3 ohm range and at 65W, the vape is warm and quite cloudy in a dripper.
These are just what I do, I don't like fine gauge wire, I like to be able to yank the Rayon through a coil with the Leatherman...
I have a
24g single coil in my Aqua II at the moment 20W @ 0.6 ohms, the vape is a little on the cool side but more flavorful with the juice I am using than running it at 25W.
It is something you are going to have to play with to find your sweet spot, 95% of my RTAs are run less than 30W and the drippers with MaxVG I usually run at 65W.