Everyone will have different nicotine tolerances and preferences, but generally, the answer to this question is dependent on how many cigarettes you smoke (or smoked) per day.
If you are (or were recently) a heavy smoker, we recommend a nicotine strength of either 12mg or 18mg if using traditional freebase E-Liquids (for light or moderate smokers, 6mg is a great starting point). You may need to adjust your nicotine strength depending on your preference for throat hit.
Recent and current ex-smokers often prefer nicotine salts, as they look and work like 50/50 E-Liquids but provide a much smoother throat hit with a higher nicotine strength. With Nic Salts, we recommend starting at 20mg if you are a smoker looking to make the switch.
Using too little nicotine when you first start to vape after quitting will most likely not satisfy your cravings, so we recommend going higher at the start and then weaning yourself down as your dependence on nicotine lessens over time.