1. Paris Métro and tickets
The Métro is an excellent and convenient way to get around the city. Paris is a walkable city but the trains will get you there quickly. Places that a regular visitor will end up going to in Paris are covered by the train system. Get a carnet of 10 tickets for €12,70 and use a ticket each time you ride the train. Since they are actually 10 individual one-way tickets, a carnet can be shared among you and your travel companions or family, or even just for yourself. The tickets can be purchased from the ticket machines at the Métro station. If you've used up all tickets, you can easily buy another carnet from the ticket machine.
2. Spend time at the cafes
The Parisian cafe culture is evident in every area at every corner. Parisians spend a lot of time at cafes sipping espresso, wine, or beer. Take your time at the cafes and join the locals appreciating some idle time. Take a seat at one of the outdoor tables for some people watching. You will notice that the cafes have outdoor seating arrangements such that all the chairs face out to the street making it conducive for people watching. Parisians love their street view very much so.
3. Reservations at restaurants
Making reservations prior to your visit is recommended as restaurants like to know ahead of time who is coming in that night. Generally speaking, you are welcome to stay as long as you wish for the evening/night at your table since the French way of dining is a relaxing affair where you enjoy the meal and wine with no sense of urgency. Therefore, if you are planning to go to more popular restaurants you should plan on making reservations instead of just doing a walk-in. You can generally walk up to the restaurant a day or two ahead (or call) to make a reservation but for the very popular ones (e.g. Michelin-rated restaurants), plan on making advance reservations. This is not to say that you have to plan your meals to a T- it is still fine to do walk-ins at other casual cafes and restaurants.
4. Interacting with the French
While most of the older French generation may not speak or understand much English, the younger generation can at least speak and understand adequate English. Learning useful phrases like s'il vous plaît and merci certainly helps. Greet a store employee or restaurant server bonjour. If you make an effort to speak simple French phrases to them, it shows that you take some interest in learning their culture.
5. Ordering wine
Wine is such a quintessential part of the French dining experience so don't miss out on it, unless if you can't drink wine. The French drink wine over lunch and dinner. Restaurants always have a house wine in addition to their wine list. You can't go wrong in going with the house wine, red or white. The quality of the house wine at restaurants are generally better than those you will get in the U.S., and not to mention affordable. Order the house wine by the carafe, bottle, or glass. Une carafe de vin rouge/blanc, s'il vous plaît means "A carafe of red/white wine, please." Depending on the restaurant, some do carafes or bottles. Bouteille is for a full bottle; demi bouteille is for a half bottle. Un verre de vin rouge/blanc, s'il vous plaît means "A glass of red/white wine, please." If you don't specify the type of red/wine, it is meant that you are getting the house wine. Enjoy the wine with a meal.
6. Stay smart and be safe
Paris is a beautiful city and unfortunately just like other European cities, there are pickpockets. Visitors worry about pickpockets prior to arriving in Paris and that is for a valid reason but don't let this be a paranoia. Be smart and aware, watch your bags, and don't put your wallet or purse in an easily reachable spot. If you get approached by the gypsy petition girls, wave them off. If you someone pretends to have found a gold ring and asks if it's yours, laugh it off and walk away.