Thanks for bringing this up, because I am having the same problem. Right now, I'm using Google Adsense, ShoppingAds, Commission Junction, and a couple of key sponsors. I also take donations.
I have no idea what to charge my sponsors, and I have more people who want to sponsor. Right now, the sponsors are in a rotating banner, and on the links page. I charge them by the month, and they generally pay me for a year in advance. Unfortunately, I have no idea if I am charging "enough."
Commission Junction has been of no value to me, and I may give up and drop it. Google is up and down, with no rhyme nor reason to it. ShoppingAds is OK, but isn't going to make any of us rich. My Google Page rank is only 3/10, and I haven't done much to shift it up.
