Bring plenty of 1's and 5's for tips and misc. When on a boat be firm on what you want to do. Alot of times they like to take newbies on boat rides trolling for marlin. If they get one great--but sometimes the tuna can hitting like mad and you would not know. Find out in town what is biting and where and tell the captain. Act like you have been there before and there is less chance of them messing with you. There are numerous reputable fleets and boats. Stick with them. Don't go for the guy who is hawking it down by the docks. They usually have inferior equipment--fishing and/or boat. If a deal sounds too good to be true-------it probably is.
Stay away from the Giggling Marlin or Squid Roe the night before you fish and you will be ok.
have fun.