Watch out for pickpockets!
I got my wallet stolen out of my purse in the middle of Monoprix while I was shopping for groceries.
Unique Suggestions: Make sure that you always have copies of all your important documents in another location. Always know exactly what's in your purse and wallet. Report all theft to the police station located in the comedie opposite the Opera House
Don't give the homeless people money! There are a ton of teenagers and young adults who sit on the street with their dogs and harass you for money. Don't feel obligated or harassed into giving them any.
If someone starts harassing you just keep walking and ignore them, they'll give up eventually.
Unique Suggestions: There's an old woman by the Polygone who you can feel free to give money to.
I found the French Riviera to be very over rated. It is overcrowded and overpriced. But then again, maybe I'm being a bit unfair. Having just come back from the beaches in Brazil, I find it difficult not to draw the comparison.
However, on the plus side, I found that the illumination of public monuments and buildings at night was excellent.
This city is so big. There is so much to see. Bring along a map and choose what you want to see before you go.