10 factors determine how much profit you will make from your AdSense participation.
1. How much traffic your site gets
2. How many pages on your site host AdSense ads
3. What the click thru rate from each page is
4. What the value of each click is
5. How many ads appear on each page
6. Where these ads are located
7. What format these ads are in - size, location, layout and color scheme
8. Google's fractional pay out rate
9. How much of your site's traffic is from new as opposed to repeat visitors.
10. How valuable Google regards your site.
To maximise your site's profits from AdSense you ideally should optimise all these factors. However, some are out of your control: Google's fractional payout rate for example. This is the percentage of the revenue that Google earns from a click that it passes on to you.
Google doesn't tell you it's payout rate at present but you can run an experiment to find out what it is.
Optimising the factors that affect your AdSense income could take you some time so what you should focus on initially are the factors that are going to work in your favor most quickly with the minimum effort