First of all, do you understand exactly what "stock photography" is all about? Not to burst your bubble, but most stock photography agencies have specific requirements, including the equipment used. Let's just say that you're not going to be selling anything to stock agencies when you're using a P&S camera.
Are the images you are currently getting out of your present camera of sufficiently good resolution that they'd look fine when blown up to sizes beyond 8 x 10? Someone making a purchase to put on his or her wall expects a high-quality image with high resolution and usually decent presentation (ie, matting/framing). Are you familiar with the printing process and matting/framing processes required to sell prints? Most photographers who sell prints of their work do NOT print them out on their own printer at home.
Are the images you are currently getting out of your present camera well composed, intriguing, with a certain "something" that catches the viewer's attention and definitely has a "wow!" factor?
The photography business is a highly competitive one and very difficult in which to get a foothold. Starting out by taking courses and by assisting a professional photographer out in the field or in the studio can be one way to learn more about the art and the business of photography. Many photographers start out as apprentices to others long before they finally are ready to take the plunge and establish their own business.
Go to the library and/or bookstore and grab some books on photography -- not just the "how-to" techniques books, but those which include many photos by famous photographers. Look at those photos, study those photos...appreciate them for the art that they demonstrate. For example, right now I've just brought home a new book from the library, HARRY BENSON'S AMERICA. When I look through the images there, I won't just be looking at the famous people present in many of his photos, but will be studying the lighting, the angles of the lighting, the way in which he composed the picture....and I'll try to guess at how he interacted with his subjects during those portrait sessions in order to get the results displayed on the pages in front of me. You can learn a lot from studying the work of others before you ever pick up a camera.
After spending some time in really looking at photographs, THEN go out with your own camera and play around with some of the concepts and ideas you've just seen, work with your camera to see what kinds of images you can produce. Shoot in black-and-white, see how there is a different thinking process there than when shooting in color. Try and figure out why one photo excites you while another leaves you thinking, "ahhhh...."
Again, while at the bookstore or library, be sure to pick up some books which give clear descriptions of the business of photography. As has already been mentioned, it IS a business, and like any other, requires legal advice and support (tax laws, y'know), a good business plan, and an investment of money. For most people, yes, the investment is going to be in the equipment, but also in the time one puts into this. Many photographers continue to hold a day job while doing their photography "on the side" at weekends and such until they reach the point where they can afford to be a professional photographer full-time. And by the way, the definition of "professional" photographer is that one earns income from his or her work. It has nothing to do with the quality of said work. I've seen work from professionals and from so-called amateurs which is equally outstanding.
Since you're still in school, if there's a photography club, you'd probably get a lot out of joining that, or if there is a local community photography club, go to some of their meetings and chat with people who are approaching photography from various levels of expertise.
Most importantly: get out there with the camera you have and use it. Learn from it....
That's a quick swing, no?
