The Sud Lípez, a province in the Potosí Department, is a sparsely-populated, visually spectacular area of Bolivia. And, as in many of the areas of Bolivia, infrastructure access and public transport are variable, and challenging.
In this sparse area, here are the choices:
Vehicle: rent a car and drive: you'd have the advantage of setting your own pace, stopping wherever and whenever you wish. You do need to plan ahead, know where you're going, and where you are, GPS indispensable.
Cycle: If you want to be completely on your own, you might consider bicycling. You'd need to prepare yourself, and your kit, but it can be immensely rewarding. Two Brits, Harriet and Neil, share their Andes by Bike adventures and offer detailed and insightful suggestions.
Tour: joining a small group with guide, riding in a 4x4 on the tourist circuit, and guaranteed to take you to the iconic locations.
Local bus: As most Bolivians travel by bus, buses go pretty much everywhere. In the sparsely populated Altiplano, you can go from village to village, but you'd need competent Spanish, as the be willing to tolerate irregular schedules.
Camión... for the truly adventurous, and very inexpensive: stand on the side of the road and flag down a passing truck.
And an admonition: isolated and on your own, wandering off-road onto random tracks, you need to be prepared for extremes in terrain, weather, and temperatures, and be able to get yourself back to a populated area.