I would tell a newbie to take everything in stride.
Don't let a few bad apples spoil your trip.
Jamaicans are beautiful people, too bad some of them have to sell trinkets, instead of going to medical school or becoming a marine biologist.
When you are approached by sales people, think twice, look, but don't touch, if you decide to buy, make sure it is what you want.
Some sales people think that once it is in your hand, you have agreed to buy it.
If you don't want something, just say no thanks with a smile.
Don't let a sad looking face or a mad looking face intimidate you.
Stick to your guns.
Once you look a person in the eye, and say no thanks, you don't even have to keep looking at the person.
If you were walking, keep walking.
If they have 2 arms and 2 legs, they will be fine.
They may try to look (pretend)upset, but that is life.
Jamaicans, like most folks, respect confidence.
So, be confident, walk tall and be a little kind, if you can, to the real folks that do need help.
Use your head at all times and dont be a scaredy cat.