The bus system in Buenos Aires can be a little intimidating for newcomers but in reality it is a great and cheap way to navigate the city if you known what to take. A great way to get familiar with the bus system is to use the website Como Viajo . The concept is simple. Enter in your starting address followed by your end address and Como Viajo will give you the fastest possible route by bus or a combination of bus and the subway.
When starting out, it is very tempting to take a taxi everywhere. The fact is, for a lot of routes (some, but not all), you could take a bus or use the subway and arrive at your destination faster. This can usually hold true if your route is through a more residential area or at an off peak hour where the bus is not stopping every minute to pick up passengers.