To get around the city on a budget, use the Metro system. A 2-day unlimited Metro pass is €20. Taxis and ride-sharing apps are options but can be more expensive and may encounter traffic.
For a more leisurely visit, consider adding an extra day or half-day to your itinerary. Book tickets in advance to avoid long lines. Paris is very walkable and bike-friendly. Take a stroll through the picturesque streets, and indulge in Parisian cuisine at the local street markets.