David,


A good starting point would be to set your camera to Av
(Aperture Priority) and set the f-stop to f/8. This will give you a
fairly deep DOF but is a large enough aperture that your IQ should not be degraded due to diffraction.
See what that gives you and go from there. If you tell me more about
what you are shooting and what you are trying to accomplish I could
probably give you some better advice