How do You Increase Adsense Earnings?

Hi,

I have been submitting lots of articles and working on links to my few sites the last few months and it started to pay off in some fairly good adsense earnings, then suddenly two days ago and again today, for no apparent reason, my earnings have gone down more than 50% ? Why is this ? I thought I could work on getting more impressions over the next few months to get that extra second paycheck, so to speak, going up and up, but maybe a person can't expect that from Google Adsense ? Is it too unpredictable ?

Those of you who are earning lots with Adsense (e.g. $70.00 or more per day) - have you ever seen this, and to earn more, is it just a matter of building more sites with more and more content, and it all improves eventually ?

Related to more page impressions/traffic and more clicks, is a blog attached to your site (in directory) a good idea or not ? I tried that last month with my site at http://www.weight-loss-discovery.com, but I haven't seen any boost in much of anything. I also have a site at http://www.skin-care-reviews.com that gets quite a bit of traffic from the SE's, but my earnings per click have gone down ever since I added that tower in the left nav bar.

Anyway, could some of you who know how to succeed with Adsense, please give us little guys a few hints as to how to increase income over time ?

It would be much appreciated !

Thank you.