Short stays (1-4 days): Get a Navigo Easy card (€2 at any station) and load single tickets via the Bonjour RATP app. Singles are €2.10, but a 10-pack is €14.90 — Buy the pack if you're taking more than 7 trips total.

Weekly Navigo (€30): Only worth it if you're staying Monday-Sunday AND taking 15+ trips. Covers all zones including airports. Must buy by Thursday for current week.

Day passes (€8.45 zones 1-3, €20.85 all zones): Overpriced unless you're doing 4+ trips in one day. All-zone version only makes sense if hitting Versailles or airports.

Airport connections:

• CDG: RER B direct to Châtelet-Les Halles (€11.45, 35 minutes) — Use Exit 7 at CDG Terminal 2

• Orly: Orlybus to Denfert-Rochereau (€9.50, 30 minutes) then metro, or RER B + Orlyval (€13.25, faster but pricier)

Essential app: Download Citymapper for real-time departures and platform changes. Métro runs until 1:15am Sunday-Thursday, 2:15am Friday-Saturday. Line 14 is newest and has platform screen doors — Use it when possible for speed.