For public transportation, buses and minibuses have a fixed route throughout the city. The cost per ride is very economical.
Taxis are also extremely inexpensive! When using taxis make sure to agree on the tariff before getting on the vehicle, as there are no meters, and that way you are not overcharged. All taxis within the main part of Cusco have a fixed rate of 2-4 soles (meaning 65 cents to a little over a dollar). They should not overcharge you. However, they may charge extra if going to an outer part of the city, or if they have to enter the airport, as they are charged for entry. If you are going to the airport, ask them to drop you off outside the airport if you would like to avoid the additional cost. Be careful and watch your surroundings when entering the airport.
The city is very walkable and abounds with tourists, however, always make sure to walk in groups when going to the Plaza de Armas (main square) or to other areas of the city.