Keep in mind when it comes to wire gauge (thickness): The thicker the wire, the lower the resistance. In other words, current travels easier through thicker wire.
For cloud chasing, you want a long pull so that you can fill your lungs with vapor. This is why single coil builds are pretty much out of the question, because they're usually around 5-6 wraps and made for short bursts. What you want for cloud chasing is a relatively cool vape that takes awhile to heat up, so you can take a long draw. This is just my opinion of course, but for me, the ideal cloud chasing setup has been:
- 3mm ID
- 26 awg
- 7-8 wraps
- dual coil
This gives you a 0.4 - 0.5 ohm build with a wide open coil (3mm) for plenty of wicking.