Reddit reviews Paris Was Ours

http://www.amazon.com/Paris-Was-Ours-Penelope-Rowlands/dp/1565129539
This isn't a practical guide per se, but it talks extensively about what it "feels like" to live in Paris. I found it to be super-helpful.

http://www.absparis.org/fr/_fileup/telechargements/pdf_telechargements_10.pdf
This is the guide that my exchange school (in Paris) sent me when I was accepted to study there. A lot of the details (like where to buy textbooks, etc) won't apply to you, but there is still a ton of useful information in there.

The rest is personal advice:

Cell phone providers: the big two are Orange and SFR. There are other smaller, "no frills" providers like Simyo that you can also investigate. Most likely, what you'll want to do is buy a pay-as-you-go SIM card to use with your existing phone. Orange and SFR charge 40-50 cents a minute, Simyo charges 15ish. Just beware - if you have an iPhone from AT&T, you won't be able to put another provider's SIM card in it. If you need to you can get a phone for 10 euros or so.

Grocery stores are everywhere. The major chains are G20 and Franprix, and they're pretty equivalent, as far as I can tell. Of course, you can also buy food from individual shops / outdoor markets.

Tips are almost always (99%) included in the bill. If you feel that your waiter was phenomenally wonderful and is your new favorite person in the world, round the check up to the nearest denomination that you have (i.e. if your bill was 33.50, you can round up to 35 if you want). Say "c'est bon" (it's good) as you hand them the money to let them know that you don't expect change.

Cars: You don't need a car. In fact, you don't even want a car. Paris is probably the single most pedestrian friendly city in the world. What you'll want is a Navigo subway pass. Basically, these are cards that you can pre-load with money, and then swipe to get on to the metro.

You can also check out the Velib bike system. Basically, there are bikes in bike racks all around the city. You check one out for 1/2 euros a day (there are also weekly, monthly, and yearly plans) and then pay a small amount per hour until you return it to any other bike rack. Warning: You'll need a credit card with a chip in it to sign up for this system, and American credit cards don't have them.

There are a million other details that I can't think of now. I'll probably come back and edit this post a few times as I start remembering them.

EDIT: Be careful about ordering water in restaurants. If you just order water (de l'eau), you'll most likely be brought bottled water (eau minerale). By law, all types of eating establishments have to offer free tap water, but you need to know how to ask for it. Une carafe d'eau is a pitcher of tap water, and will be free.

If you have any other questions, feel free to ask. I'll be living in Paris until May of next year, so if you'd like meet up and grab a beer or whatever, let me know.