I have a few websites on various niche topics, all running Adsense. The most promising one currently has a CPC that hovers around $1; the rest have CPCs of $0.25-$0.50.

I'm curious to know what on-site factors affect CPC. That is to say, what I can do, legally (in white-hat compliance) to increase my CPC?

Some factors that affect CPC but are not within my control (and therefore, beyond the scope of my question -- they're just examples) include:

• What advertisers are paying for keywords on my site
• What pages people are landing on
• etc.