Great thread so far, I think this thread has attracted some successful adsense marketers and they have shared some very sound advice.
I think the main point throughout this thread has been to work hard on your adsense sites to make them not only profitable, but stand the test of time in the SERPS.
Another think I'd like to add to this thread is: If you have not already done this, start it as soon as you can...
You must have a hobby or interest you're into, read about online e.t.c... if so... start a blog about it, make it a site that's really yours with those finishing touches of a dedicated webmaster, keep it updated at least twice a week, get involved with the community on twitter, facebook, or youtube e.t.c..
You eventually will see the backlinks, visits & followers roll in, once the site is awesome, look at where you can make money from it, and unleash your favorite black hat tactics a few link layers deep.
You will roll in the cash, especially if your hobby is a sport such as golf or fitness
