Hello, I am not new to photography, but I am new to commercial photography. I have been shooting personal images and portraits for customers, but now I am getting some offers to shoot commercial work. I wanted to ask some basic questions like how do I charge for commercial work when the customer will be using my images on billboards and signs? I know this is a broad question and maybe you guys can point me to a website where I can research the topic more. I know when I started doing portraits you guys pointed out basic ways to charge people and I wanted to get something like that for commercial photography. I know there is a lot more about copyrights and laws, but for now I would just like an idea.