Visiting the city of Teresina will give you some options that you could choose as a way to get there and the ways to go around the city. If you will go by plane, you can land in the Teresina Airport that serves various airlines that you could use. There is the Azul Airlines, TAM, and Gol and they also have additional regional carriers that are small. If you travel here then you must book in advance because it could give you a headache when you are rushing as you have to pay an expensive fare.
There is also a bus that you can ride if you would go to Piripiri and to Parnaiba. If you decide to have a car you can do so but it is not recommended that you will drive at night for safety reasons. That is because theft and robbers could work well at night as the environment could really help them also. The highway or streets could be lined up by the division of crops that can cause an accident.
You may suddenly hit an animal and that could lead to an accident. If you are in the city then you can use the bus as a mode of transportation as you can go in many places using it. There are also taxis that is affordable and it is a better alternative than renting a car. There is also the light rail that you could take when you do not want the others or used it as an alternative.