On Fri, 4 Feb 2011 16:26:19 -0800 (PST), cubby
wrote:

Is there a foolproof way to do this, other than meticulous measuring?
I never seem to get it perfect first time, and then once the screw
holes are made it's difficult to reposition. I'm sure someone on here
has a cheat.

Do you mean alignment with the latch/bolt?

If so, you can use lip-stick. Placed on the end of the latch/bolt.
Close the door -- operate the latch/bolt back and forth to mark the
position on the door jamb. From that mark you can figure the location
where the strike plate needs to go. Mark with a pencil and mount the
strike plate.

If not your meaning, I give up G.