Questions to experienced texture artist/painters


I have some questions for texture artist, who work or worked on movies, and doing high end texturing. I have 3-4 models that i modeled over few months. I am thinking to texture them for my portfolio. So i can practice texturing and painting as well.

I would like to start with first question is, how do you search the right reference images for your texturing? I once watched a video on youtube, is was a guy from Method studios, and he said that, always search the right reference photos for your models.

The second question is, how do you prepare a photo, before to be used? The thing about prepare is i found people remove lights from images, Why? And how to clean a image in Photoshop?