Personally, I don’t like to carry a lot with me when I walk, especially anything on my shoulders. One of the nice things about walking along the Riviera is that towns are so close, you don't need to.
You can carry a small day pack with you if you're comfortable with that; I haven't found it necessary. I get away with just cargo shorts (the more pockets the better!) and a money belt or fanny pack. I fill them with my wallet, maps, cell phone, camera, pocket journal, paper, pen, sunblock, lipbalm, mini med kit*, tissues, and lots of snacks.
I'd also recommend mosquito repellant. It's not a big problem and I've never needed it that, but some people tend to attact them more than others, so bring some just in case.
For shoes, I wear regular sneakers. If you prefer hiking boots, that’s fine. Whatever you bring, just make sure they’re closed-toed (no sandals due to rocky uneven surfaces) and well-broken in before you arrive. I'd also recommend bringing a second pair of walking shoes just to have a fresh pair, or in case one pair gets wet.
And I know I'm not your Mom, but bring a hat!
* Mini Med Kit: we recommend you bring the basics like band aids, ointment, aspirin, and blister treatment - minor stuff.
For weather information on the French Riviera, our Recommended Links page has links to 10 day forecasts & monthly averages in Nice.
The French Riviera enjoys over 300 days of sunshine a year. The trick is knowing which ones they'll be!
So just in case, I'd throw a small umbrella and a light rain jacket in your suitcase.
Finally, because this isn't a typical tour and your guide won't be concentrating on history, dates and other facts along our walks; if you'd like more in-depth information about the places we visit, we recommend bringing a French Riviera guide book with you.