Is it safe to travel alone in nice, France?
Nice is pretty safe, but always when you travel, with or without others, you need to be safety aware. Behave like you would in the big town near home, or if you live in the big town, like you would when going to an unknown to you suburb. Make sure you have your money stored safely, most of it in a pouch under your clothes with your passport. If a street, or a cafe, looks like you would not feel safe there, do not go in. And do not go into the park at night. When you meet people you will have to make a decision who to trust and how far, but I think you should always be a little careful. Do not get totally wasted, drunk or otherwise, in company of people you have just met and do not go home with (strange) men. I think you know the long list too, most mothers tell their children these things all their life.