mmm well what age range would you like to play as? I'm assuming from bottles you mean baby bottles so if we assume you like to play that age range than you should pick up a pack of disposable adult diapers/nappies and some form of baby toy. Even if you aren't planning on using the diapers it will help you get into character plus if you're like me then you'll simply enjoy wearing them.
Beyond that just finding someone responsible and experience to be your big is about all you'll need to get started once you get a feel for the fetish you'll want to start looking into products meant for adult babies such as baby style diapers in adult sizes, swim pants, and adult sized onsies.