I just went through this exercise yesterday and was able to save a substantial amount of money! First research what options are available for you, in my market it is primarily Spectrum (local cable company), Verizon Fios, and Directv. Besides your local cable company here are some options:
Next find out what specials/pricing each one has for the package you want. Now call up your current provider and tell that you wish to cancel and see what they say. I currently have Directv and when I called to cancel they were all of a sudden able to offer me a monthly price of $40 which is 60% lower than the $102 I am paying now!!