We find images to be a decent supplement to text. But we also prefer to avoid photographs. There are more than enough decent 2D images or 3D renders out there that can be used, even if one has to trawl through fifty times that amount of unsuitable images to find them. Still, there is little that beats the satisfaction of having drawn/modeled/created the image you use yourself.

Tumblr. It's easy, and never fails me.

Reddit, sometimes. /r/ladyboners and /r/gentlemanboners provide a plethora of male and female models/actors, despite their silly names.

TheEvanCat said
I use words because I believe that finding pictures is lazy.

I don't think it's lazy. On the contrary, I think it poses a unique new challenge. Often, I find a picture before I do anything else. Then, using that image, I craft my character. I can base everything off a facial expression, a prop, or an item of clothing in the image. Person has a tattoo or piercing? Tweak their background to explain why. I don't think it is lazy or cheating in any way. It is just a different approach.

To answer your question, OP, I generally use Google or Tumblr.