First and foremost, find out what battery you have. That's absolutely crucial to mech mods. It decides what your limitations are. If you want the best performance within safe use you need to know the continuous amp rating. Find out what it is, then go to google and type it in and add the name "Mooch" he's probably run tests on it to find the actual ratings if it's not properly labeled (happens a lot with companies like Efest, MXJO, and others).
From there there's lots of options. .3Ω is probably a good starting point. Steam-engine.org is the website Joeyboy is referring to. 26g is IMO the best starter, you can do a lot with it. Cotton, I like Koh Gen Do, cheap and easy to find plus easy to work with (just cut strips off the pads and remove the backing). I bought a box of it from Nordstroms about 6 months ago that I'm not even half way through, though you can find it cheaper other places like Amazon.
http://vapingunderground.com/thread...-sick-clouds-bro-thread-sticky-edition.78126/
That link may help you, lots of great information in there. Mechs are no joke, so do some research on safety, and stick to those rules. From there for the best production you want to get close to the limits, but not exceed them. (if it's a 15amp battery you're cut off at .29Ω, 20amp .21Ω, Ohm's Law (amps = Volt/resistance, a=v/Ω, so whatever your continuous rating is you don't want to be higher than it for the amps).