Professional photography is a business. It's also an art. Artistic people tend not to be businessmen and vice-versa. This is the fundamental downfall of most aspiring photographers, they simply are bad at marketing. Here's a truth that may very well change your life: The best photographer in the world, may make almost no sales. The worst photographer may make millions of sales. The difference is that the worst photographer was a great businessman.
It's tough to comprehend at first, but pure artistic talent may never get you anywhere as a professional. You must also view your photography as a business. If your anything like me, you've been viewing photography as an obscure, and tough-to-market business. This is not the truth.
So how do you find clients? Don't just sit in front of your computer hoping they will stumble over your name or website and call you up because your so good. It's not going to happen. You need to be going out and networking. Walking into businesses even if you think there is no chance they would ever need your work. You'll be surprised at how easy it is, and how many people actually are interested in hiring you for your time and talents.
How do music bands make it to the big time?? In Today's environment they set up a myspace page and put their music up, but this alone does not drive them to the top. They network. They go to any clubs or bars that they may be able to play at and introduce themselves. That's what we need to do as photographers. People drive business, so go to the people and land some business.
Hopefully I've put this all in a way that makes sense to you, because for me it was a revelation. Market hard, shoot well, and good luck!