There is a difference between being a professional photographer and being a financially self sustained professional photographer.
Professional means to get paid to do it. To do that you can tell your friends and family that you will charge them $5 to do portraits for them. But that will never make you a profitable photographer.
Let me say I do not make my living on photographer, I don't want to. I did it for a while and started falling out of love with it. Why? The business part of it. I went to the New England School of Photography in Boston. I suggest you look into it. It is a two year program taught by photographer for photographers.
After your skill is good enough comes time to create the business. If you like business and know business good. You will either have to be able to run a business or will have to hire someone to do it. Think financials, advertising, social marketing, networking etc. (The financial part is what I don't like.)
You will either need your own money to put into your business or you will need an investor. Depending on if you plan to have a studio or not will greatly influence the amount of money you will need. Costs: Equipment, Rent, Insurance, Marketing costs, Chamber Memberships etc.
The key to making it is knowing your strengths and marketing them. Do not under price yourself. You will most likely not be able to compete with chain store pricing, so don't try. Pride yourself on great photography and market yourself.