Couple of tips. Everyone seems very nice and they will reach out to help you, carry a bag, get a door etc.. However they are doing so to get a tip. If you want that service fine if not make sure you have you grab your bags, open doors, etc before someone does it for you.
If you go to the falls you will need sandals. You need either water sock type sandals or sandals that have the velcro straps. Flip flops will not do.
Bring your own and have them on. Their will be vendors around the gate that sell them but it is a rip off.
Their will also be people who will be carving stuff out of wood and sometimes they might start to carve your name as they approach you playing it off as they are giving it to you for free. They are not. That's how they sucker you in. Just look the other way keep walking DO not say your name and jus tsay no thanks or ignore them.
You will also want a disposable water proof camera. Buy them here in the USA for you go. Some places rip you off and will charge up to 50.00!
Ocho rios is a nice place of the eastern side of the island. Its pretty safe even at night. Visit the falls, plantations, and if you can make it up to the blue hills for coffee.
The currency is USD bring lots of ones five etc to tip and use to buy stuff so you don't need to make change.
Don't order jerk from any places like Margrarita vill, Hardrock etc... The best Jerk you will find will be at the some rest stop or shack on the side of the highway.
Some pics
I also always rent a car and drive. They are RHD and people drive like its nascar. Buy the insurance and who cares!