I've consulted various methods for learning Greek on the subject of pronunciation. Practically all come up with a lot of very theoretical information about sounds, diacritical marks, assimilations and permutations. But give very little help as far as practical application of said information is concerned.
And some actually go as far as to ignore pronunciation altogether!

I then decided to pronounce ancient Greek as I understood it - not the modern Greek way - and let others decide for themselves whether they accept my pronunciation or prefer to do it differently.