My first instinct was similar to Accompong's comments, to tell you it's the same as anywhere...other than Jamaicans tend to be more polite and more formal in their daily greetings...very British in style...maybe I'd call it a bit of an aloofness compared to an overall American personality. My information is a generalization.
But, then I remembered there are some aggressive higglers and hustlers that may approach you...which can be intimidating to newcomers or people that are shy in being approached...you've received some good information above from those that have dealt with them before.
Fist bump, hand shake...all appropriate.
You're going to hear the words "good night" in the late evening/nighttime as a greeting not to be confused with saying goodbye, but to be understood the same as we would say "good morning" to each other.
Enjoy yourselves...relax...go with the flow...
the sun is shining, the birds are chirping, the sea is calm and a dirty banana or rum cream in your coffee is an excellent breakfast starter.