http://www.deviantart.com/ is the best place for art freak,
art lover, photographer, designers to get online stock photos resources, to expose your talents,
to get commision art, and to share your art through the world.. it contains millions of arts which will make you feel regret to watch it.. cuz it is so addictive.. it contains, Many things from product concept, character design, logo and icon design,
and variety of art from manga, comics, drawing, line art, pop art, traditional art such as water color, air brush, graffiti, word art, tutorials, and etc. watch it.. and you Love it!
Anyways,The easiest way to get watchers is by joining deviant art groups. There you can expose your art work to lots of audience.
Other than that
Watch as much people on DeviantART that you can, and hope that they do watchbacks. I've also managed to get a few watchers from giving out llama badges.
Or the second one, the best way is that you could get more watchers by making a good art. Or manga-styled art.
Or you can make a fan art too :)