Buenos Aires is generally safe, but as in any big city, crime (especially theft and robbery) is a concern. Avenida Rivadavia divides the city into north and south, and as a rule of thumb the neighborhoods to the north tend to be wealthier and safer, offering more amenities for new arrivals. Meanwhile, the areas that lie the closest to the Microcentro (downtown) are a bit rundown and not the most attractive places to live. The best areas to establish residency tend to be Recoleta, Palermo, and Belgrano as they are further away from Microcentro, have a less transient population, and are near embassies and diplomatic residencies. The Belgrano area is especially valuable for families because of its many private and international schools.
San Telmo is a trendy selection, and many artisans congregate in the area. However, try to avoid nearby La Boca and Constitución, which have poor reputations for crime and unrest.
The city has a wonderful public transportation system, and depending on the area, it can be a good idea to find a home near one of the main subway (or Subte) lines. The D line runs through Palermo, Recoleta, and Belgrano, and the stations tend to be relatively safe and clean. The western stops on the B line (running through Almagro and Villa Crespo) are also recommended.