Then I made the mistake, I used the money to improve the website and attract more visitors and let them stay longer. Result 1.500 visitors a day who watched 6 pages in average instead of 1,6. But my Adsense income dropped down like crazy to les as 5$ a day.
At first I didn't understand what went wrong, but later I did get it. My visitors found what they were looking for, and that is why they stopped clicking the Adsense ads.
So my advice if you have a MFA website, don't make it to nice, make it very clickable.