Don't get wasted, don't accept drinks from strangers, learn the language before you go there if possible and you'll be fine.
There's more to this city than tango and dulce de leche (although there is a lot of both, and rightly so). Potentially my favorite South American city, Buenos Aires is filled with European architecture, beautiful people, old-world charm, and delicious food. You could do a foodcation here without trying, and then you'd be amazed at the caliber of food and presentation at relatively economical price-points compared to what you'd pay back home. There's a lot to see here, but you should probably check what locales are closed on what days so that you don't get excited just to arrive at locked gates. There are numerous neighborhoods, all with differently distinct feels, all with something worth seeing.
Incredible! This city is magical and it really draws you in.. from the food to the people to the night life, the grand boulevards lined with trees, the asado, the tango, it is all very romantic.
Buenos Aires Touring is a very helpful trilingual, family based tour operator , with emphasis on personal attention and punctality at reasonable rates.