Did you see Dan Burn's header last night, scoring the first goal for Newcash? It was so majestic, just ran and solidly planted his nut on it and it powerfully rocketed with curve in off the back stick.
One thing I know for a fact, you don't have to whip your neck and flail your head at the ball; treat your body/neck/head like a concrete bollard. If you've ever crossed a football at a concrete bollard, it will rebound like a rocket. So 90% of the time you don't need to generate more power, you just need to be concrete and that makes accuracy 100 times easier, no need to flail.