depends on what kind of photography you want to do. If you want to be a portrait photographer, wedding photographer, sports photographer, journalistic photographer, etc. We have a few professional photographers here on MC.
Start up a website with your work is the first thing I would do and then you need to start building a client base and figure out who your marketing towards.
You can always start by getting a higher end digital SLR and start shooting. Learn your camera well. You'll start shooting your friend's wedding (while a guest) and it can lead to be hired at actual weddings too (though it's not as easy as you'd think).
To be a good photographer... all you need is a camera. Even an iphone is good practice and produces really great shots.
Also many magazines and newspapers take public submissions as they are always in need of general scenes or stock photos to accompany articles. Contact those to find out their submissions policy. Some require hardcopy prints but others will let you submit a digital image. Almost all of them will pay you for any photos they accept. Then start submitting your best photographs (and they need to be near perfect as far as exposure and composition is concerned).
"Screw with my pixie dust at your own peril!" - Mr. Wiggins
Basically, you need to sell yourself any chance you may get.
Put a business card on public bulletin boards.
Put your work in photo contests.
Get a small booth at the county fair.
Get a small booth at one of the local arts and crafts markets (especially good if you do it in a touristy location, like near a state park and such) -- best of all, you don't even need to man the booth. Just pay your monthly fee and they do the selling for you (just like at an antique shop).
Ransom notes (my favorite is, "Buy my photos or the rabbit dies").