When adjusting the intonation on your guitar first loosen all the strings and relieve tension on the neck. The reason for this is you are about to tighten or loosen the truss rod. The truss rod either removes the bow in the neck or gives it a slight bow. Now when turning the the truss rod make sure to only do quarter turns at a time. Too much turn could bow the neck severely causing permanent damage.
-Thomas Suggs, Music Instructor