When arriving - going through Immigration can be a bit time-consuming. You wait in long lines and the air conditioning is very limited in this area. Once you clear Immigration, you pick up your luggage and go to Customs. The time to clear Customs can vary enormously, depending on whether or not a Customs Officer wants to closely examine the contents of your luggage. They are often concerned to know if visitors are importing electrical items and you are very likely to be asked about that. After clearing Customs you are on your way to your final destination.

Give yourself extra time when departing the airport.  The lines for Air Jamaica stretch across the entire airport.  After check-in you still need to go through the security lines.  It is okay to spend some time at the airport waiting once you are checked in - as there are many restaurants and duty free shops. 

When returning home, don't get stuck in the long lines and crowds in the first liquor store.  There are two more along the concourse for gates 8-16.  No waiting and same prices!