Is it better to take the bus or Metro?

Take the Metro for speed; take the bus if you want to see the city sights while moving from point A to B.

Do I need to tip taxi drivers?

Tipping is not required, but rounding up to the nearest euro is common for good service.

Navigating Paris as a couple

Prioritize walking, use the 'Citymapper' app for real-time transit updates, and avoid the RER B train late at night. Focus on one arrondissement per day to minimize travel time and maximize time spent together.

Master the Metro. Download the Bonjour RATP app or use Citymapper. Buy a Navigo Easy pass at any station for 2 euros and load it with a 'carnet' of 10 tickets to save about 20% compared to single-ride paper tickets.
Prioritize walking routes. Paris is compact. For trips under 2km, walk instead of taking the Metro. Use the 'Passage' shortcuts between streets to avoid main traffic arteries and discover hidden courtyards.
Manage the taxi/ride-share situation. Avoid hailing random cabs. Use G7 for official taxis (they have a specific lane privilege) or Uber. During peak hours (8:30 AM and 6:00 PM), the Metro is consistently faster than any car.
Handle luggage on public transit. Avoid taking large suitcases on the Metro during rush hour. If you must use the RER train to/from CDG, keep your bags locked and physically touching your body at all times to prevent petty theft.

Is it better to take the bus or Metro?: Take the Metro for speed; take the bus if you want to see the city sights while moving from point A to B.
Do I need to tip taxi drivers?: Tipping is not required, but rounding up to the nearest euro is common for good service.