Smoking: Smoking is way more common here and much more socially acceptable. It seems nearly everyone aged 18-30 smokes and then about half the people beyond 30 continue smoking. In fact, every single person in my friend circle under the age of 30 smokes. Cigarettes are very expensive here, Marlboro is about $11 a pack, so it is very common to see people roll their own cigarettes. You can buy your own paper, filters, and tobacco separately or buy a tin from a big-name brand that comes with all of that. Smoking is no longer allowed in public buildings, but people will crowd around the front door or strike one up right in your face while having a conversation outdoors. It is also allowed at outdoor seating in restaurants and cafes.
Bathing: It seems like an odd topic, but there are some differences that made me blink. For instance, I drove myself crazy trying to find a cloth shower curtain when I first got here only to find out that they don't use them. You know how in the US we have the plastic shower liner on the inside and a decorative cloth or plastic curtain on the outside? They only have the liner. Also as I discovered while in the hospital, many people use thumb-less mitts (think a washcloth folded in half with the sides sewn shut) to wash with instead of a washcloth or those loofah balls. It is also true that some people tend to practically bathe in cologne or perfume. Typically men and women past 50.
Fashion: Even though Paris is the fashion capital of the world, it's not too crazy here. A look of elegance and sophistication is typically the normal fashion here. Cleavage is tactically hidden to show only a hint of it, except for one fashion in summer where one wears a see through (either sheer or loosely knitted/crocheted) shirt and uses the bra as an accessory. Bras do not have the same negative stigma of "must be conforming but hidden" as they do in the US and seeing a bra strap at the shoulder or the form of the bra through a thinner shirt is no big deal. Makeup typically goes one of two ways; absolutely nothing or tons of makeup but still with the air of looking natural, you typically do not see color much outside that person's normal skin tone. Nail polish is hardly worn and jewelry is sparse. Hair is kept in simple styles and unnatural dye colors are not common. The scarf is a must have accessory and the particularly fashionable or stubborn will be seen sweating it out in 90° weather because they won't discard their dress scarf.
The Check: This one is a little more well-known. At a restaurant the server will not bring you the check. It is considered rude as it could be taken that they want you to leave. When you are ready, you go up to the counter and pay. You do not tip. If you feel the service was incredibly exceptional, the best you've ever had in your entire life, you can leave one or two euros. (Note, I have never seen anyone tip except once when a man didn't want his 20 cents in change back.) Another thing of note is that during the course of the evening if you want something you must summon the server to you with eye contact and a subtle hand raise or you get up and go to the server for your request. Do not snap your fingers or shout out. It is very normal for a table to stay at a restaurant for 2 hours and they are not going to check on you every couple sips and bites to see if you're okay, especially since a small restaurant will only have one server and larger ones will have 3, maybe more if they are also a pub and drinks are ordered frequently. In general they will be there for the beginning drink and menu orders and to clear plates before the next course arrives. One last helpful hint, do not call your server by shouting "Garçon!", it's highly insulting as it literally means "boy" and was once used to define someone of a lower social rank. The popularity of calling a server a garçon came from a French movie in the 80's of the same name about a sixty year old man who is the head server at a pub. Much to the demise of French servers, the movie was universally well received and thus the whole world began calling servers boys while visiting France.