There is a constant stream of taxis running right in front of the main entrance. During very busy times when there are many people hailing cabs, you can get one faster if you walk up the block closer to Mercado 10 de Agosto so that they are not all taken by the time they reach you. When hailing a cab, extend your arm out horizontally. It is considered rude to raise your arm above your head to hail a taxi. Just watch how the locals do it.
If you do not speak Spanish, it is helpful to write the address of where you are going on a piece of paper, unless you are going to a well-known location. The majority of taxi drivers speak little or no English.
Taxi fare to most locations is $1.50 - $3.00. There is a minimum fare of $1.39 (daytime) and $1.67 (nighttime). The taxi will charge the minimum fare if the taximeter reads less than that. It is accepted practice to give a minimum of $1.50 always.
Although most taxi drivers are honest, occasionally you get a taxi driver who “accidentally” forgets to turn the taximeter on, and then quotes you an inflated fare when you arrive. It is the law that taxi drivers are required to use the meters. If your taxi driver forgets to turn on the meter, just politely remind him to turn on the taximeter (“¿Puede poner el taxímetro, por favor?”). If the driver fails to start the meter or tells you that it is broken, take another cab.
A small tip is very much appreciated, but not required or expected. Personally, I usually round the fare up to the nearest dollar.