The Sacred Valley is reached overland from Cuzco. The two standard routes are via Pisac (1 hour to the southern end of the valley) and via Chinchero (1 hour to Urubamba and the centre of the valley). Both roads are paved and well-served by buses, colectivos (shared minivans), and private taxis.
Colectivos to Pisac leave from Calle Puputi in Cuzco throughout the day; to Urubamba and Ollantaytambo, from the terminal at Pavitos. Fares are around 8 to 15 soles per seat. A taxi for the full day from Cuzco runs about 200 to 400 soles depending on the route and waiting time.
For Machu Picchu, the train station at Ollantaytambo is the main departure point. PeruRail and Inca Rail both run multiple trains a day. There is also a smaller station at Urubamba used by a few daily services. Booking ahead is essential, especially in the dry season.
The Cusco airport sees a redirect when the new Chinchero international airport opens (timeline uncertain). Once operational it will sit on the plateau above the valley and dramatically shorten the arrival route for international flights.