Paris offers a great transportation system. The Metro is cheap and runs across the city. The Single-use ticket costs €1.90, and a travel pass for two days can cost €10. However, it's advisable to walk as most attractions are located within walking distance from each other.
If you have more time, explore more of Montmartre's artistic neighborhood, including the Picasso Museum and Lapin Agile. On the contrary, if you only have less time, you can skip Musée d'Orsay and spend more time at other attractions. Weekends tend to be busier at most tourist attractions, and it's advisable to make bookings in advance to avoid long queues.