What to bring?
Bring shoes you just slide on, you don't want to be trying to tie shoes or anything.
Bring your toiletries - toothbrush/paste, shampoo and any other hair stuff, moisturizer, lip balm.
Bring loose comfortable clothing. Keep an eye on weather forecasts so you pack appropriately.
Bring small bills, in case you buy anything, you don't get pesos as change.
I'll add if I think of anything else.