Useful Advice

- Create an account on The Fork. It takes less than a minute, and you can then use the website to book tables pretty much everywhere (like OpenTable), but it also features special discounts of up to 50% off your check. There is no need to prepay (unlike sites like LivingSocial).

- Parisians generally regard having lunch before 12:30 p.m. or dinner before 8 p.m. disgustingly provincial. Avoid that. Eat with the locals! Besides, who would want to eat in an empty restaurant? Note, however, that lots of restaurants will refuse to serve lunch after 2:30 p.m. or dinner after 10 p.m. So you have a fairly narrow window for meal times at most establishments.

- You should ALWAYS greet shopkeepers, waitstaff, and others (like the RATP person you're asking help from) with a friendly "Bonjour !" The French guy's observation:  French people are often very self-concious of their English and hate being addressed in Shakespeare's tongue from the start. Always break the ice with a few words of French, even if you only know two or three. In the American guy's experience, that--along with appropriate use of "Merci, madame/monsieur" and "s'il vous plaît"--convinces the French person that you are not simply another one of those devilishly rude Americans who rushes in expecting and demanding everyone to speak English. 

- Taxis are reasonably cheap, and since the end of 2015, all take credit cards. When you see a white or green light on, the taxi is available; a red light (or if the light on the roof is off) indicates it is occupied or otherwise unavailable. Always make sure the meter is engaged once your journey has begun. Uber does work in Paris (chauffeurs are actually more stylish than in New York); just use your Uber account as you do at home. Of course, to use Uber, you’ll need to have access to wifi or turn on data. 

- Paris is a safe city, and one can walk around or take the subway/métro at night without fear (although the system shuts down every day between roughly 1 a.m. and 5 a.m.).

- Still, always be aware of your personal belongings, as talented pickpockets are everywhere. Never respond to the request of a beggar boy or girl or other young person to sign a petition (usually in support of the deaf and mute); it's a scam to distract your attention. Do not leave your phone or camera on your table, even if it's directly in front of you when you are sitting on a terrace and even if the surroundings looks quiet and there doesn't seem to be anyone around. I once saw a group of young pickpockets storm a terrace and leave with all the valuables in under three seconds. Use a lock for your backpack (especially in the subway), and never carry your wallet in the back pocket of your jeans. If you follow this basic advice, pickpockets will generally move to easier prey.