Make sure that the glue is evenly distributed around the taper. It's been my experience that that is what causes most alignment problems.
Make sure the ferrule is hot enough to make the glue run easily then twist it at least two complete revolutions before final seating.
This will make some guys groan, but I like to put the point on something like my vice in the shop and tap the adapter LIGHTLY with a hammer.
Not so hard that you deform the tip of the broadhead.
Using steel adapters you can be a little more "assertive".
It's the odd adapter or broadhead ferrule that doesn't match up with the other.