A couple of my friends just got married in Jamaica in early May, and I spent most of a week there. That place is a hell hole. Like Sharky said, DO NOT GO OFF THE RESORT! Jamaica is a third world country and you are viewed as easy money. You are viewed as easy money by thugs and police alike, so just try to stay out of any and all trouble. Marijuana is not legal there, but the only people that get busted are tourists b/c tourists are the only ones with money. I don't think Jamaican jail would be a pleasant experience, so just try to be good.
If you are travelling with women, then do NOT let them out of sight at any time. Rape is basically acceptable there as long as a tourist isn't the one committing the crime (that's basically how all crime works there). It sure seemed like the majority of Jamaican men will solicit your wife for all kinds of things as you are walking down the beach holding hands, so if you think there'd be much pause for them if you weren't there, then you're kidding yourself. I saw this first hand, and it's no BS. It's one of those things where you figure out very quickly that things can go south in a heartbeat, and you are severely outnumbered and therefore helpless. Very few people in the wedding party ventured off the resort after the first day.
I brought a 4 D-cell Maglite with me and carried it whenever it was dark, even on the resort. I got made fun of for having it the first day, but the comments suddenly stopped by the second day. You can't have a gun or even mace/pepper spray so you'll have to carry some kind of blunt weapon that isn't a weapon. Since the island is filled with tourists with no weapons and lots of money, being seen with a big metal club makes you not worth the effort.