Image searches don't really boost your traffic. People looking for pictures aren't interested in the content of your site, they just want the picture.
That isn't always the case. In most niches image search traffic is quite useless. There are a few niches that strive on image search traffic...celebrities, fashion, wallpapers, porn, art, etc.
It do bring traffic to your site since google images will show first your website before the picture. Best way to get visitor to your site is by putting the "alt" tag to your image code. There's wordpress plugin that can do this easily. Also remember to use keyword in the picture title just like what above said.
I've used this technique on one of my arts & crafts site. The images actually brought almost half of my search engine traffic to my niche site. I don't know how to convert the stats to check for subscriber or ads-clicking conversion, but traffic-wise the traffic's increasing non-stop.