Guayaramerín has a small airport serviced by TAM (Transporte Aereo Militar) and Aerocon.
From La Paz, it's a painful, slow, mostly dirtroad travel. The "Empresa Yunguena" travels every day but the schedules are totally unreliable. It's approx 20 euros (feb 2015)
The town is small enough to reach most places on foot.
If you are not planning on coming back later to Bolivia you'll need your passport stamped in both Bolivian and Brazilian post. Bolivian posts open everyday 8 Am until more or less 7-8 PM. Brazilian side Policia federal is less pleasant experience they open few absurd hours during the weekend (6 to 8 AM, useful if you are an early waker and want to go from Braz to Bol but not the opposite) and even when they are due they don't really excel in pleasentness.