To start off, you will need
1) A camera..... And I believe your phone comes with one. Nowadays Camera phones cam be pretty impressive....
2) Know your camera and read about the common photography techniques (be it about composition or long exposure etc.). Learn it's limits about what it can do and what it cannot.
3) Once you hit the limit of the equipment and it still can't achieve what you want, you will then list down what you want in the new camera that you want to look for.
4) Set a budget
5) Start browsing some camera reviews sites.... and make some decisions based on your needs. *If have to, just rent it out for a few days*
To note, your question is phrased very broadly. There are many genre of photography.. From Landscapes, Macro, Portraits, Sports, Underwater, Aerial etc. Know what you are interested first before you talk about it as a hobby.