Find a pro shop you're comfortable with and get set up right. It'll save you headaches and cash, in the long run. A lot of them have used bows, or know of someone who upgraded and wants to sell one. Most are more that willing to help you get started because they depend on repeat business from satisfied customers.
Just get something that fits you, feels good and, is set up properly. It doesn't have to be the top of the line speed demon , either. Most of my stuff is 15+ years old, fits me, shoots well and, kills deer just as dead as the new stuff.
Good luck and have fun.