Having experience it first hand, I would offer these suggestions: 1) Do not "look rich" - no jewelry, expensive handbags, watches, etc. 2) Avoid any "crowd commotion" - favorite diversion tactic of thieves is to create a ruckus such as a young woman appearing hurt on the ground, small children who look pathetic and when the cruisers stop to "help", their bags and purses are snatched in a second.
Besides the druggies who steal to feed their habit, people do not realize how poor and desperate many people are in some of these locations. They love "cruisers" cuz they are not there long enough to file a police report, press charges, etc. so their crimes go unnoticed.
I am skeptical of some of the reported robberies of guided excursions because a)most of the guides carry weapons and b)they are in constant communication with their "base". They would need to slow down for the road block, stop the vehicle, etc etc. There are also a lot of excursion companies that have one passenger who is actually a security guard.
So be cautious, stay with the pack, and try not to let it deter your port fun!