First of all, your friend can start by advertising that he or she does this kind of work. He also needs to get a portfolio together and can offer local companies a free trial. This way they will see your work and know that you are serious.
Isn't there something on ODesk.com for photo artists as well? I'd check into that too. It's a great site where you can bid on jobs. There are tons of places online for freelancers of all sorts.
An ad and a portfolio. Those are essentials. Or better yet, he can put together a website of his own to put his work in and use that to apply for jobs. There's a lot of free hosting service that would welcome great content.
One place that would be good for your friend to check out is rentacoder.com you can find a bunch of various type jobs on that site, you can make a decent amount of money if you spend the time to see what work is available and bid on the work.