I'm thrilled to help you with your travel plans to Nice, Cannes, and Arles, these beautiful cities located in the South of France. Here are some travel tips for you.

Best Time to Visit:
The best time to visit these cities would be during the late spring, specifically May and June, or during the early autumn, from September to October. During these periods, the weather is remained warm but not too hot to enjoy your visits.

Route and Accessibility:
Most international travelers usually arrive first in Paris and take a domestic flight to Nice, from which you can get to Cannes and Arles by car or train. You can use TGV or Eurostar service to enjoy rapid and comfortable train journey around these cities.

Accommodation and Booking:
There is a wide variety of accommodations available in these cities, from luxury hotels to budget-friendly pensions. Consider booking your accommodation well in advance if you plan to travel during busy periods such as the Cannes Film festival.

Clothing and Essentials:
A combination of light and comfortable clothing is recommended. Also, don’t forget to carry a good sunblock, hats, a good pair of sunglasses, and swimwear if you plan to explore the beautiful beaches.

Health and Safety:
In general, these cities are considered safe for tourists. However, it's advised to stay vigilant for pickpockets in crowded tourist areas. Keep a copy of your documents with you and carry a basic first aid kit. Always stay hydrated, particularly on hot summer days.

Local Etiquette and Respect:
French people value politeness, so remember to say 'Bonjour' (Hello) and 'Merci' (Thank you). It's also common to greet locals with the phrase 'Excusez-moi de vous déranger' (Sorry to bother you) before asking a question. Respect local customs and traditions.