Nefta is only half an hour from Tozeur, but couldn't be more different. Tozeur is a busy desert town which thrives off tourism and is now something like an Aladdin-themed fairground buzzing with tour groups. Nefta is very much a laidback yet conservative town where tourism takes a backseat. Given the proximity to Tozeur, I'm surprised more tourists don't visit.
Anyway, if you're in Tozeur and find it all a bit much, hop on a Nefta-bound louage for a couple of dinars. There are plenty of them throughout the day, so you won't have to wait long.
In the opposite direction, Nefta is a starting point for those heading to Algeria, and I saw louages on themain street waiting for passengers for the border town of Hazaoua, half an hour to the west.
Louages dump their passengers on the main street in Nefta between Oueled ech-Cherif and Ez-Zaouia quarters before the bridge over La Corbeille.
As Nefta is located in the desert, a jeep might come in handy to get there and to travel further into the desert. Please however take care not just to drive arround: the algerian border is very close and crossing it is not at all appreciated.