Everything about Paris seems mythical and magical—even the drugstores here induce envy. In truth, it is mythical and magical, but also easy-to-navigate and understand once you have the basics down. So, let's get to it.
Getting there: I have always flown in and out of Charles de Gaulle airport. It's a huge place so definitely give yourself at least the two hours pre-international flight. You have to stay pretty alert once you're there to keep track of changing gates, the multiple security stop points you have to get through, and all the duty-free temptation. As odd as it sounds, I find the food options strangely lacking and always bring food with me from Paris when I'm flying out.
There are taxi stands at the airport that charge a flat fee to bring you into the city. You can also call an Uber easily, or take the train into the city and then hop on the metro or get a cab. I am typically pretty bleary after a redeye international flight and go for the 55 euros cab in (where I promptly pass out).
Getting around: Look down. See those feet under you? I recommend those for getting around as much as you can. I average about 20,000 steps a day in Paris, because the wandering is so much a part of the experience. That said, there is smart walking and dumb walking. Don't do the dumb walking like trying to cross an entire bank when there is a perfectly good subway that will get you there in half the time with a tenth of the wear on your feet. The Metro is awesome. It's clean, it's simple, it's rarely super crowded, and you can get a data signal in the tunnels if you need it. You can use the RATP website to route, and Google Maps often does a pretty good job. The Metro machines will dispense your paper tickets with English instructions and they take US credit cards. Just keep your tickets as far from your phone and wallet as you can as they tend to de-magnetize the strips, which invalidates the tickets.
If you don't want to walk or metro (no judgement), Uber is very popular in Paris. It's a little cheaper than taxis, and you can get picked up exactly where you are. You can hail a taxi or you can get one at a taxi stand, which are all over the city. BUT, you cannot hail a taxi within a certain distance of a taxi stand. So if you see taxis with green lights passing you by, look around for the line of taxis nearby and walk to it. Most taxis do take credit cards now, but it can't hurt to have some cash on you. There are also rentable bikes in Paris, but I've heard of trouble renting them without a European credit card. I haven't tried it first had, so just passing along what I've heard.
Getting oriented: Paris is sliced basically horizontally by the Seine river, and the two sides are connected by a series of bridges (and the metro below ground). The Right Bank, or properly La Rive Droite, is the top part of Paris if you look at it on the map. The Left Bank, or properly La Rive Gauche, is the bottom part of paris if you look at it on the map. Get it? Right = top, Left = bottom. Get ready, they use cardinal directions all the time too. Within the banks, there are a series of arrondissements, which amount to neighborhoods for your travel purposes. They each have a different vibe and different things to visit/eat/shop. Don't be intimidated to go across the Seine—something being on the same bank doesn't make it closer or easier to get to, depending on where you are staying.
Getting less overwhelmed: I personally really like taking the bus tour in Paris the day I arrive (the one I've taken a few times is right by the Louvre, which is an easy location to get to). It gives you a sense of where the landmarks are and general layout of the city, while allowing you to sit still and slowly regain your bearings in a new timezone. Contrary to the stereotypes, I have found Parisians to be welcoming, helpful, and radically better at English than I am at French. If you are lost or confused, ask the staff at a restaurant or hotel. Seriously, don't be scared to ask. I also put a ton of data on my phone and Google constantly. The Google Translate app is awesome and saves me all the time.