Be aware their job is their profession, not a trade they’re temping at to get through school or a step in their career path. To get a waiter’s attention say: “S’il vous plaît, Monsieur/Madame.” Don’t call them over until you are ready to order and try to know what you want; their time is valuable.
A golden rule that will serve you well in restaurants and just about any place you visit (even elevators): say “bonjour!” (“bonsoir!” in the evening). This doesn’t just mean hello.
It’s recognized French code for, “Yes, I am here, and I am respecting you by being polite, so you are going to respect me and maybe even be pleasant to me.”
You’ll be amazed — it works.