How do you troubleshoot a latch that is misaligned?

If your latch is not properly aligning with the strike plate attempt to determine how the latch is misaligned by performing the tests below.

Vertical test
To test if the latch and the strike plate are properly aligned vertically use a thin straight edge like a flash card or piece of paper and align it with the top or bottom of the opening on the strike plate. Attempt closing your door and see if the latch hits the straight edge. If the latch is hitting the straight edge the strike plate will need to be moved up or down accordingly.

Horizontal test.
To test if the latch and the strike plate are properly aligned horizontally, first check when attempting to close the door do you press hard to get the latch to extend? The latch should extend when the lock is in a natural resting position. If you have to apply pressure to the door to close it equal pressure is being applied back to the locks latch which may eventually damage the latch. Adjust the strike plate so the latch is not pushing against the strike plate when the door is in a closed position. 

After determining where the misalignment is taking place make the necessary correction and then reinstall the strike plate