Good Cameras for semi-beginner photographers?

I have a question for all you photographers out there. I'm 15, and I have been into photography for about two years now. In Christmas 2011 I got a Kodak Easyshare camera, and I absolutely loved it and have been using it ever since. It was great for just getting started in photography, but it definitely isn't as fancy as some of the stuff out there. I really want to get serious about photography and start a local business someday fairly soon. I enjoy it so much, and I've even gotten quite a few compliment! I just don't know what exactly to look for since I'm so new to this, and I don't want to end up with something just like what I have now. Does anybody have any idea of something (or a few things) that are a step above what I have now that would be helpful to take my pictures to the next level? I was thinking about a Nikon, but once again, I really have no idea what I'm looking for. Any ideas? Thanks so much in advance! And by the way, I should probably say what kind of pictures I take. I do a little bit of everything. People, nature, a pair of antique binoculars… You name it! Just whatever inspires me. And I always like to take it from an artistic perspective.

Canon EOS Rebel T3i is a great camera.

Nikon D3200 or D5200

Sure would help to know how much money you can spend. Is your budget $200.00? $300.00? $400.00? $500.00? Without knowing what you can afford its pointless to make any suggestions.

Please EDIT your question and tell us your budget.

I'm 15, and I just bought myself the Nikon D7100, but if you can't afford that I'd suggest the Nikon d3100 or d5100. Another good option is the Fujifilm HS30exr if you don't want to have to buy lots of lenses