With your next inhalation take a little more air and a little more time.
With the next exhalation take a little more time and expel a little more.
Repeat until you are jerking the final step of the 'in' to get that little more, and twitching a cough to force out that last bit on the 'out'. When you are down to about 4 long "in's" and "out's" a minute, you will be deeply at peace.
A change in temperature on the top of your head probably means you are not exhaling enough, please stop and relax.