Photoshop complex compositing & cosmetic cleanup advice

I am a veteran photographer and have been using Photoshop for many years now but I use it primarily for tonal, color, and saturation adjustments and cropping of course.

There is an employment opportunity that I am interested in that fits my profile except that it also requires experience in cosmetic cleanup and complex compositing. I was wondering if someone out there would have advice or links to some tutorials regarding these topics?

Thanks,
Gene