For the least effort you shift your press and release a bit earlier in time than your drag.
press and hold (to start it making vapor)
about 1/2 to 1 second later start dragging
continue to drag and about 1-2 seconds before you are done dragging
let up the button
and continue dragging out whatever vapor remains in the mouthpiece
That way you are dragging when the vapor is best
Typically you drag e-cigs a bit slower than cigarettes (you don't want to out-pace your atty because then you would get more air in your vapor). And you drag into your mouth then inhale. And let your nose smell some of the vapor because smell is a huge part of flavor. SOmetimes I let some waft out of my mouth so my nose catches it on the inhale.