First Time Buenos Aires

Hola,
I will be in Buenos Aires from Protected content of August. As this is my first time there I would appreciate every advise.
What to do, what not to do?
How is the best way to move around?
What to see?

Due to a business trip I would have leisure time in the evenings.
It would be also a pleasure meeting you for a drink.
I might stay in San Isisdro.

Thanks in advance
Stephan