follow the manufacturer guidelines as a starting point, if you haven't already
the instructions of any good speaker maker will take into account the dispersion pattern of said speaker
Toe-In or Toe-Out
I always listen for a long time, with a bit of toe-out, just behind my head. But I try again, for the second time, and for my room, I find the sound is much more coherent, with less saturation, in fact I can play a little bit louder without fatigue and saturation of music, like just in my face sound. In fact it is more easy to listen to my music. It is not a big move to make, just experimentation, it worth to try, for free.