This tutorial is requested by - on my tagboard. Hope this helps you!
Actually I get most of my pictures from photobucket or yahoo images. Say, on my skin [kick] I search for converse shoes and then I vectored one of them.
The best place to get pictures is definitely stock.xchng, but DEFINITELY NOT threadless.com and deviantART, unless you have permission from the artist. Please understand this is image theft. There's a difference between images from stock.xchng and threadless/deviantart. Stock.xchng carries stock images which means they're free for commercial use (but do provide a link back) and the people who submit their photos gave permission for you to use pictures. Threadless and deviantART pictures are NOT for commercial use and by using an image you are stealing it and violating the copyrights.
It's not about leaving a link back to the artist, but what's important is that the artist give you permission to use the image.
Stock.xchng pictures are equally nice too. Please do not use Threadless and DeviantART (especially pincel3d's artworks) stuff anymore. I've got my stuff distributed by this girl on her site, it makes me angry to have my things taken without my permission and this is how the other artists will feel too. And you can put yourself in their shoes: how would you feel if someone took your skin but never left a credit back?
I hope this helps you and please prevent image theft in Blogskins.com.