Generally Santiago is a safe place. In Praia, like in every capital in the world, you have to be more careful for pickpockets. Take Taxis at night and don’t walk along empty roads.
The City of Tarrafal is fairly safe. At night, if you walk in empty streets, go in groups.
For hikers on the island of Santiago, the police and the goverment recommend to hike just with a local guide. Ask at the Reception in Casa Strela for further information.
Useful phone numbers: Police 112 / 132 or +238 266 11 32