As fmica said, Bolivia is one of the poorest countries in South America and there is social unrest with the local governmnt, and it is by all means best and reccomended to go with an expert tour company which will keep you out of any danger zone while still enjoying the beauty of this country.
The best trips in Bolivia is Las Paz and the unreal Uyuni. The link below as more informaton on Uyuni and Bolivia in general. The company, Peru for Less, really does a good job and great prices with Boliva packages.
http://www.peruforless.com/destinati..._bol-uyuni.htm
Ric