Expose it like it is a sunny day (i.e. follow the sunny 16 rule).
Most people radically over-expose the moon because the meters average over the entire sky. Also, shoot a high-speed on a tripod. That will help against atmospheric distortion.
I use aperture 8 or 5,6, low ISO and a time, that matches with my tele-lens (1/500 or else). For results look at my moon-gallery. Please view the photos in size original, all other sizes are not good for moon-photos