Probably one of the biggest mistakes I made was not realizing what a huge impact the right keywords had on my success. Not only did I not choose the keywords carefully I didn't use them for their full effectiveness.
For example I'd slap any ole name as the name of the page as long as it was marginally related to the topic. Not a good idea. Use the keyword phrase as the name of the page and the file.
I didn't check to see what AdWords paid for the keyword phrase. That affected my AdSense revenues.
For example *eliminate bad credit* only gets 170 global searches and has a cpc of 5 cents. *repair bad credit* gets 12,000 searches a month and has a cpc of $6.46
That one word change from eliminate to repair makes a big difference in your ADSense revenues and has more people searching for it.