Depends on your equipment and how well it delivers nic. I vape 12mg currently. Smoked camel filters. But I was using 24mg nic when I first started, but have dropped down as my equipment improved. Generally what level make you not crave a smoke is good. If you are getting to much nicotine at your current level the drop down, if you are not satisfied then increase it. 12-18mg should do you fine. But a lot has to do with your gear, the amount you vape, and most importantly, what keeps you off cigarettes.