Are you looking to have a good time in Paris? What a silly question! Of course, you are! That's why you came here!
Well, when dinnertime rolls around, hop on the Metro and work your way up to the Abbesses station in Montmartre. When you come out onto the street, look east toward the post office (a yellow/blue building marked La Poste). That is rue Yvonne le Tac. Walk east two blocks until you come to rue de Trois Frères and turn left (uphill). Shortly you will come to number 17, a red-fronted building and the most memorable dining experience in Paris for under 50: "the best fondue restaurant in Paris" one of my friends once called it.
The City of Paris levies a tax on wine-by-the-glass. Le Refuge des Fondus escapes the tax by serving their wine in baby bottles (biberons). It's not great wine; to be honest, it's not even good wine; it's the French equivalent of Ripple, but after one or two, you won't notice, and the fondue is excellent.
You'll be seated either facing the wall or against the wall (which requires you to climb over the table, because there are no breaks between tables). You'll be seated next to people you've never seen before and may never see again. They may speak English, or they may not, but they and you will have a delightful time nonetheless.
The girls in the background are two such. One lives in Paris; the other is visiting from South Africa. We rubbed elbows at dinner then parted forever. If we should ever meet either again, it will probably be here, because we will all be back.