You have a camera and now you should have the needs to fund your new obsession, if it's not an obsession i hope it quickly becomes one.
First you should decide how you want to make money, what i mean to say is what do you want to shoot to bring in revenue. You could go commercial and shoot for a company or shoot products such as jewelery or clothing or even buildings. Another is through the art of it, you can take beautiful pictures and sell them at shows or online. You can shoot portraits that range from models to babys and pets and anything in between. My favorite though is wedding photography. One wedding can land you anywhere from $1000 to $5000 and the workload isn't as bad as you think it is.
So you should figure out your pricing before someone actually proposes buying your art. Don't ever feel guilty about your price. If someone is willing to pay $200 for an hour shoot then go for it, if someone isn't willing to pay that then politely apologize and walk away from the situation. It's one thing to negotiate but don't just drop your price because they can't afford you. If someone says i really want you to take my picture but i don't think i need a full hour, then you can drop the price a wee bit. As far as selling your prints, don't negotiate; this is your art and you shouldn't compromise.
See my post about shooting weddings, it's worth the trouble if you can call it that. One wedding can buy you a 70-200 lens and a MacBook Pro, think about that.
So starting a business one of the basic things that you want to do is go to City Hall or your Town Hall and apply for a business license which will cost you anywhere from $15 to $50 max. With this business license in hand you can go down to a local bank and open an account in your businesses name. This is essential so that you can track your finances better with your business.
So now you need some swag for your business, your letterheads, business cards, shirts and invoices and contracts. You can either brand yourself or not brand yourself when it comes to this. Basically do you want to stick with one theme or not care at all, that's for you to decide, i'll be posting more about that later on in another post.
So i know there's a million other little things that go along with having your own business, i'm not going to get into those million little things. The point of this post was to get you excited and to get you to take those first step. Some of what i said may apply to you and some may not, but take those first steps and figure it out for yourself; there lies a life of possibilities.