I was taught to start pointing at the side to which you will turn. i.e for turning right you start looking out to the right then do the full 180 across the front, then over the top and back to the right before tipping in...

Unfortunately, the official training manual which holds details of the full technique is "...not for release to the public without...", but I suspect you get the gist now. :ok:

Not a military instructor (just a lowly civvi PPL instructor :( ) but I was taught to teach start at the front, 30 deg segments to the left until you can't turn your head any further. Back to the front and then the other way. Throughout, keep moving head (especially around canopy frames etc). For a turn, start at the outside of the turn (ie look left for a right turn) and sweep all the way across to the inside of the turn before turning. In a high wing, always dip the outside wing before commencing the turn. In all types, when out of the turn do the opposite sweep, lifting wings as necessary.

PS. Always clean the windscreen before flight :)