The airport (El Alto International) sits up in El Alto at 4,061 metres, about 12 kilometres from the city centre by road. Taxis from the arrivals hall take around 30–45 minutes and cost roughly 60–80 bolivianos depending on your destination and negotiating. The descent into the canyon on the main road is dramatic but straightforward.
Within the city, the teleférico cable car system is the most useful public transport — it's cheap, reliable, and gives you a view. There are currently ten lines connecting the centre to El Alto and various hillside neighbourhoods. The minibuses (micros and minibuses) that jam the central streets are cheap but require local knowledge of routes. Taxis are plentiful and inexpensive by international standards; agree on a fare before you get in or use a radio taxi for security. Uber operates in La Paz and is often cheaper than street taxis.
On foot, the city rewards walking between the centre and Sopocachi — it's mostly downhill in that direction. Coming back uphill to the historic centre will remind you quickly where you are.