The capital of the Côte d'Azur is not the standard of security. When going to the beach, leave valuables in the hotel safe. Keep a close eye on your belongings in crowded places and during excursions. If something is stolen, contact the police within 48 hours. Avoid the Ariane and Moulins areas, which are considered to be a sort of urban ghetto, and avoid the dark alleys in the Old Town.
If you don't want to run into street drug dealers, don't walk along the Promenade des Anglais and in parks at night. Especially not recommended at this time to appear here girls may be mistaken for "priestesses of love". Try not to use ATMs at night. The safest area is considered to be the central part of Nice.