No real trick that I can think of. I always mount the broadhead on the adapter screwed into the arrow it will be shot on. Sometimes your arrows insert will be shifted off center a hair. A head may spin true on one arrow, but not on another.
You can align the blades to your liking when mounting it to the arrow it will be shot on. I prefer my blades to be vertical (on a 2 blade head), so I can get em positioned just the way I want.
Once I am done, the head stays with that arrow for life. If I take it off for some reason, I start the process all over again.
Good luck,
BP