Get to the Louvre real early in the morning.
Practice some French.
Be Oh So Patient and polite.
Tell them you are from South Africa - smile and say "Mandela". (That's for France only).
Don't do drugs.
Check your baggage in case some mofo tries to plant drugs on you.
If you go to Switserland, make sure you have Swiss Francs. They don't do Visa and they don't do Euros.
Make absolutely sure you have the exact train ticket you think you should be having.
Don't do brownies and that stuff. Seriously. You don't need that shit in your life. Too much trouble. Not even worth the curiosity factor.
Don't stress, have fun
Tell them you are a big supporter of whatever FOOTBALL team you hear them raving about - tentatively, if you have to.
Oh, and find out where Petra is, then take photo's while she isn't looking.
They will be worth hundreds.