To get a waiter's attention, never yell "Garçon!" this is very rude, as you are yelling "Boy!" to a man. Say Monsieur to a waiter, or Madame or Mademoiselle to a woman.
In France, being a waiter or waitress is a profession. They get paid more, have health insurance, and do not rely on tips. They are knowledgeable about food and drinks, and are proud of their job. They do not rush their clients, away, and are ok with them spending hours at the table.