Thanks for the comments and tips! There's a lot to learn for me.
Cuba sure is a special place to visit (been there for 23 days), although the 'system' takes some getting used to. Most of the time, there are limited possibilities to travel alone (unguided). Guides will warn you for danger on streets in most of the cities. However, my experience has been that guides are instructed to let you meet and talk to local people as little as possible. At least not 'solo'. So if you plan to go, don't go blind on guides
. Cubans are very open and friendly people most of the time and, if you take the courtesy to ask, they don't mind to pose for a picture.
But, as always, it is best not to wave around your expensive camera in the poorer regions of cities, or for instance harbours.