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Some sites have the following ads: dating, wallpapers, smilies, but they don't give enough revenue.
How do you think I can well monetize my site?
So, you are shocked that you are not making much money from a web-site with a broad, non-targeted demographic?
Try making the site more targeted. Specialize in a particular audience or a particular type of photo.
One thing that may help - even without changing the demographic - is to include the capability for - and very actively encourage - text descriptions and discussions of the photos.
Adsense (or whatever) doesn't know what's in the photos. If there aren't text descriptions, it can't do much to match ads with the interests of viewers. All they know is that you have photos - of some sort - and thus they can only offer very broad categories of poorly-paying ads.