Lots of really good advice in here
A long time ago when I first got interested in photography a friend saw what I was doing and wanted to do the same. He decided he would go to school to learn photography and spent two years in Daytona doing it. I'm self taught.
He came back home and became a very successful commercial photographer shooting for the local magazine and realtors in an upscale community. I didn't make money but continued to shoot what I loved and what got me interested in photography in the first place.
A few years later I ran into my friend and we talked about how our photography was progressing. After shooting a lot of surfing pictures I finally achieved one of my goals and that was to get one of my pictures published in SURFER magazine. I got paid $100 and it was my first sale and it took three years. But for those three years I did what I loved and that was spending my time at the beach. Of course I had to supplement my income with a simple job that also allowed me to spend that time at the beach.
My friend told me was making really good money but working long hours for demanding clients and the grind was making him miserable. He said when he got into photography he had a passion like me but lost it when it became a mundane job working for unrealistic people. He then told me that he envied me for being able to still shoot what I love. That moment has always stuck with me and validated my choice of direction.
That was thirty years ago and I still shoot what I want today. I'll admit that I don't have a nice car, house or bank account but my photography path has allowed me to live my dream whether it's on pit road for a NASCAR race, on the beach in Costa Rica with the guys from ENDLESS SUMER or photographing a Playboy Playmate I'm doing what I love and that makes every day worthwhile.
The point is if you want to make a living in photography pick a subject or direction that will keep you satisfied and go in that direction. Otherwise it becomes just a job.
One other thing is the internet has opened things up for everyone and everything you need to sell your photography is available to you and you don't have to rely on anyone else to make a sale.