How do I Start an Independent Book Cover Design Business?

I want to become a book cover designer, but I'm not sure where exactly to get started. At the moment, I make them for my enjoyment, and for other people on a site called Wattpad. I want to know the basics on how to start a designing business online. I'd be making covers for Ebooks and printed books.

I have a few specific questions:

Are there any licences I should get?

Say I use a photo, I can modify it, and use it for commercial use, but I have to give credit(a problem I'm having with photos on Flickr). How do I give credit to a photographer?

What is a reasonable price to charge for a cover?

How do I get myself know to authors?

Are there any other important things I should know?