If I stroll down the street, and decided it is time to eat, and see a nice cafe with tables inside and outside, and lots of people there, how do I get a table? Do I just sit down at an vacant one? Or go inside and ask to be seated? Or just stand there trying to catch someone's (whose?) attention? Are there hosts/hostesses? I already feel intimidated and I am not even there yet.
At a cafe with outside, or inside tables, I just go in and sit at an empty one. I usually make eye contact with the waitor to verify it is OK. Sometimes there will be a person at the door managing things and I just work with them. But usually it is very casual. If the place is crowded and there are no tables, I am not sure how I would approach it - probably just go to another place.
Just like in the U.S., you may see a hostess at a hostess stand near the doorway. Go up and ask for a table. She'll ask you if you want to be inside or outside. If there is no hostess stand, sit and someone will come to you promptly. It can be intimidating because it is new, but you will see that it is not different from eating out here (except your waiter will not introduce himself and won't bring you water unless you ask). Enjoy!
One thing, at a restaurant or cafe, if you deal with a host or hostess, and you want a table for 2, don't just say 'duh". Say "Bonjour-- un table por du, si vou plais" (I know my spelling is wrong). In the US it's ok just to say "two" or "two please" but this is considered rude in France. I have observed this. So take the time to practice your politeness and an easy French phrase. I am sure they will understand it if you say it in English as well, but will appreciate it more if you try it in French.
Of course there are volumes written about how to deal with French waiters - a whole different subject.
(Speak to the Snail by Stephen Clarke has an amusing take on this)
bon chance!