This comes naturally once You're used to using the Frenzel technique. You can also just open Your epiglottis as well, as then the air will be allowed to expand into the lungs.
Even if this isn't that much air, it will still be good head-wise. It is for me anyway, upon ascent I also breathe in the expanding air from the mask. (I don't have pipe goggles or anything of the kind, but a plain old sphera.
)