As in most big cities, you will need to take some precautions in order to avoid long waiting times. Make sa phone call before you go visiting a place to make sure it is open. You should purchase your transport tickets in books of ten, or else choose one of the attractive travel passes. The Paris Museum Pass gives free and unlimited access to many sites and museums and cuts down on queues. Beware that between 1 and 3 pm, most essential services are closed, as well as some museums and many banks.
Paris host 180 museums and sights open to the public, mostly from 10 am to 5:40 pm. Some propose a late opening on one day. National museums are closed on tuesdays, except Versailles and the Musée d’Orsay, closed on Mondays. Note that municipal museums (run by the Ville de Paris) charge no fee on Sundays, and are closed on Mondays.
Good to know : For 2,4 or 6 days, the Paris Museum Pass gives the bearer unlimited free access to 60 museums and monuments in Paris. No waiting line, either to buy tickets or to enter the place. The card can be purchased at any of the city’s museums and monuments as well as main metro stations, Batobus stops, FNAC ticket counters and also at the Paris Convention and Visitors Bureau.