Check if all travel documents viz passport, visa and ticket are OK.
Don’t openly display valuables such as mobile phones or digital cameras and consider using a padlock on suitcases or backpacks.
Find out about local customs and dress, behave accordingly and obey local laws - there may be serious penalties for breaking a law that might seem trivial in India.
Take photocopies of your passport and other important documents and keep these separate from the originals when you travel.
Cuba
Take care of your belongings viz Camera, Mobile etc as these may be snatched away by miscreants.
Haiti
Kidnapping is major problem in Haiti. Take proper precautions and avoid going out during the night.