In one of our first cultural lessons in French class we learned that the customary greeting is to give bisous - kisses on both cheeks (although its really more like brushing cheeks while making a kissing noise). The textbook also stated that it's perfectly normal for guys to give each other bisous but in reality I've witnessed this occur very few times; guys generally shake hands with each other while bisous are reserved for guys greeting girls or girls greeting other girls.
For the longest time I was in the habit of only giving bisous when the other person initiated it. On the one hand it is a very French thing to do and seeing as I am not French, I would personally feel like a huge tool if I made it everyday practice. Furthermore my impression of non-French people who do this is that it's a cheap trick in an attempt to come off as being sophisticated. (I don't care how many times you've been to Paris Fashion Week, Rachel Zoe, but the fact remains that you are très Américaine). But more importantly I don't particularly like being touched. Think about it. Someone else's face brushing right up against yours, especially if it's a person you just met seconds ago for the first time? For me it's way too intimate. Handshakes, hugs or fist bumps seem more proper, but maybe that's just me.
It used to be that when I recognized someone going in for the bisous I would sort of stiffen, like bracing myself for contact. Thanks to my internship, though, I've learned to adapt.
Whenever anyone entered the kitchen the first thing they did was systematically say, "Bonjour," to each and every person. For 99% of people this also involved bisous, with the one exception being the founder of the pastry shop; he shook your hand, or your wrist if you were in the middle of something and your hands were dirty. And this is perhaps what I found most surprising: that people - even those whom you hadn't officially been introduced to - would stand next to you and wait until you paused, turned, and said hello. This could be uncomfortable at times because certain individuals at work went a little heavy on the cologne/after-shave/whatever scents guys use.
My etiquette was terrible, apparently, because I should have been making this a habit since day one. It's not that I considered myself exempt from exchanging pleasantries, but as a lowly intern I figured no one would really notice or care if I didn't. But one morning after pecking one of my friendlier co-workers on both cheeks, she told me I ought to go around and personally greet everyone. Naturally I was only told this about halfway through my time there. No wonder no one talked to me at lunch; they all probably thought I was antisocial.
Personal issues aside, this custom seemed quite counterintuitive in an environment that placed such great emphasis on speed and productivity but, well, French people. In America I'm pretty sure making eye contact and uttering a simple, "Hey," even from across the room, would suffice in most situations.
The one positive of bisous as far as I've experienced is that some people full on kiss you on the cheek. So if it's say, a hot guy, you can pretend that the gesture isn't completely platonic. Trivial, I know, but a girl can dream, right?