I too love to 'shoot the moon.' I have learned that I must use a shutter speed of 1/15 or faster. I have also learned that on different nights, though the eye cannot tell a difference, there is a large variation in clarity of atmosphere - astrophotographers and astronomers know this. As a result I try to be prepared to capture different sorts of images as illustrated below:
1) Very clear (to the camera) night (blue fringing is my error in post-processing). http://www.fototime.com/219C138DFEB9C38/orig.jpg
2) Looked clear but the camera said not, so I opted to over-expose the moon itself and get the clouds around it as it began to rise above horizon. http://www.fototime.com/B67FD93BDD3141C/orig.jpg http://www.fototime.com/B8F981617DB3FF9/orig.jpg
3) Sometimes I'm just happy to stand in the back yard and experiment. http://www.fototime.com/DEC922845EDD524/orig.jpg
4) Sometimes I can even find a use for poor shots of the moon if they have a virtue I can use in, for example, CD jewell-case cover art for sharing with friends (ie not for publication) http://www.fototime.com/EB99DCFFA1A0F5E/orig.jpg
And finally I have learned that, at least for my dyslexic self, instead of trying to remember pat formulas for lunar exposure I just start firing away, checking my LCD screen for histogram and focus, adjusting shutter speed, aperture and/or ISO as needed until I start closing in on something that looks good.
As mentioned above, I have given up trying to use autofocus. It's manual exposure, manual focus (to just a little shy of infinity), tripod, mirror lock-up, 2 sec delay and cable release all the way for me.
The Canon 500 f4.0 L with 1.4 extender and my 1D MKII, appropriately mounted on top of my tripod with carbon fiber legs is the cat's meow set-up as far as I can tell. The backyard shot above that's obviously way compensated was captured with the same camera and tripod but with the Canon 70-200 f2.8 L zoom.
Shooting the moon, because of its unique challenges, has taught me some good stuff and given me more confidence in other wierd situations.