A couple of things that work for me, regardless of the degree of cant--hold your head at the same angle, and be aware of your string hand--if you have to cant more for a particular shot, you are liable to torque the string. Other than that, go with what feels good and is comfortable. Think I cant between 1 and 2 o'clock, but most every tournament I've shot in has at least one shot that puts me in an odd position, and I have to adjust the cant of the bow for the situation.

Chad