Buenos Aires is a big city and most of the people don`t speak english. So for 1st visitors is recommended many things:

1-To do a basic tour by a group or private but in order to get an introduction about their culture. There are plenty of tour agencies you can get through internet but you need to have the time to follow their schedules or you can hire a local guide that is more flexible and prepare a nice itinerary for you or your small group. There are few of them that are well known Liz www.lizflor2.blogspot.com; or Pablo

2-Economy. The situation in Argentina is difficult so it is not easy to get this issue for an american or european person. They have two exchange rates , one is official and the other is not. The official is 50% less than the extraofficial, that means that you have to go to special hidden places to change your money. Yes! They will give you  70% more pesos argentinos. Try to go with a local to change your money at a reliable place. Please read http://www.buenosairesherald.com/

3-Tango: Is a must. If you go to Buenos Aires without spending some eve nights at tango you will loose an unique think. Ask to your hotel or guide where to go and when as this is a hidden circuit. (the local one) but the other is not (the professional one)

4-If you have more than 4 days in the city then you can visit outdoors. Enjoy Tigre and Colonia . If you have more more days then you can travel to Iguazu Falls and Patagonia (Calafate).

5-Argentineans. Look great. They are very friendly. Take care with pickpockets at the streets. 

6-Where to stay? Recoleta or Palermo or Downtown