The first thing you need to do is to get yourself into places and situations that will allow you to shoot the kinds of images you feel will best highlight the kinds of subjects you’re passionate about. So, building up a body of work, and at the same time, building up and developing your skills and your style.
As you go on, evaluate how good your work really is, by comparing it to others who are doing similar styles. It doesn’t have to match exactly, in fact, better if it doesn’t, but it needs to be able to hold its own against other photos in similar genres.
Once you feel you can shoot competitive, but original work, start reaching out to clients and companies who you feel are the most likely to use your kind of work. You’ll probably get ignored at first, and even get some rejections, but this is where persistence pays off. Keep working at it, keep getting your name and your work out there, and people will begin to recognize that you’re here to stay, and that you have the goods.
Also, being a freelancer, especially in this day and age, means constantly thinking of original and effective ways to get your work out there and in front of the eyes of the right people. That’s always been a never-ending challenge, and one of the most important things you’ll need to do.