Pardon my french / the art to tutoyer and vouvoyer

This constant question. When do you say vous to somebody and when do you say tu? As a Swedish girl with the habit of saying "tu" to everyone I meet, no matter age, social position what kind of relationship you have to the person in front of you, this was quite difficult to understand in the beginning. So I just went on and said "vous" to everyone who's wasn't my age or "an equal" (that is, colleagues who are older, classmates etc). Now I say "tu" as soon as someone else does the same, and I only "vouvoie" when I'm in very official situation. But my rule is; when someone is saying "tu" to me, I do the same. If it's not le président de la Republique that is... Here you can read more about it and do a little test if you're about to move to France and want to have a little deeper understanding.