Before writing articles or a blogpost do some research on keywords related to them and than add those keyword in your posts . Than promote them where you are doing . Your earnings will increase automatically .
you need to make some research before you start. try ti find a keyword that will pay you around $1 per click. and also try to get targeted traffic. traffic from US actually will give you higher pay for every click.
you should know some high paying kwds. For example loan based kwds and change your niche according to that kwds..definitely you will get good money...
for camera... i suggest cctv keyword just my 2 cent. throw away unecessary ads block. remove text link. provide 1 or 2 ads block. when you have too many adsense on your face. your ads show all cheaps ads. simple thougth. when ads space are limited. google will choose appropriate and expensive click first. do you get the idea ?? yeahh... i know whats on your mind.. its have less click .. but its got more on $ result