Before buying any bus ticket ask to check the bus's SOAT (a sticker on the windshield - travel insurance) as some do not have it.
To La Paz take a Minibus at the main square, either at the corner of Residencial Sorata or at the corner of the Alcaldia. They leave every half hour between 3am to 6pm.
To get to Copacabana take a Minibus to La Paz and get off at Huarina. Let the driver know before so they put your luggage right. At the Huarina intersection just cross the road and wave down a bus to Copacabana. During the week this is pretty easy, meanwhile on weekends buses can be full. The same for going from Copacabana to Sorata. Or you can rent a taxi for around Bs. 450, ask at SERVICIO DE TAXI SORATA.
If you want to go on your own to the jungle area from Sorata look for a Pickup at least to Santa Rosa, because from there you can follow on with public transport: colectivo to Mapiri and then by boat to Guanay. From there Minibuses leave to Caranavi, from where you can catch a bus going to Rurrenabaque or Coroico. Pickups leave only twice a week, check at the plaza.
If you want to get to Rurrenabaque a good option is the Mountainbike and boat tour offered by Andean Epics: a little adventure and a very good option to see all levels and their different and diverse landscapes and vegetation. Starting on the first day the Chuchu pass at nearly 5000m you drop to 1100m to Consata, where oranges and coffee grow. On the second day you pass several mining villages and coca plantations. Once you are on the boat you enter the jungle. The waterfalls waiting for you on the third day are spectacular!!! The treks through the jungle make a nice difference to sitting in the boat, which is no more than 5-6 hours per day. If you are lucky the crew will get some fresh fish out of the river, but anyway the food included is delicious and plenty.