I like to do it lots of ways. mouth first then lungs for anything with tighter draw and deep flavor. But when I am using a silica rebuildable with larger air holes, I use lowest nic juice with light flavor and chain straight lung inhales, and fog up a room... this is a real joy. But another technique noone mentioned which I really enjoy is nose hits. That is, no lungs, just nose. You do this by doing a slow mouth draw only, and at the same time you fill your lungs with air through your nose. Then exhale out your nose, while collapsing your mouth (closed) and force the vapor straight out the nose.. I like to do this very slowly so that the vapor saturates my sinuses. This gives an INTENSE nose hit, the most nicotine utilization I know of.