How often do you update/ add content to your sites? Do you add articles/information or do you just subscribe to blogs?
I actually add new articles about twice a week. On one of my sites I do subscribe to a feed but that's about all I'm doing at the moment.
I add at least one original article to my sites every week to 10 days. I am thinking of experimenting with a made for adsense site at the moment just to see how it goes.