Forget "où est la bibliothèque" - here's what you'll actually need around République and Marais:

"Excusez-moi" (excuse me) works for getting attention, saying sorry, getting past people on Métro Lines 1 and 4. "Pardon" is more for bumping into someone around Châtelet.

"Ça marche" (that works) instead of formal "oui" when someone suggests restaurant in Saint-Germain. "C'est combien?" (how much?) for markets around République and small shops without clear pricing.

"Sans problème" (no problem) when people apologize for not speaking English around traditional bistros. Shows you're not demanding tourist type around Marais.

Most importantly: attempt French first at café in République, then say "sorry, do you speak English?" in English. The effort matters more than pronunciation when ordering at boulangerie.