TIP #1: The best place to buy your tickets is through http://www.airfare.com/. Don’t believe the horrible things you read about this company. They were great and extremely affordable. Most of the negative comments about this company are probably posted by their competitors.
After you purchase your tickets online, they will provide you with an e-mail with an electronic confirmation number from airfare.com. This will not help you at Argentine Airlines.
Contact airfare.com by e-mail shortly after receiving your e-mail confirmation and request a reservation number for Argentine Airlines. They will provide it for you quickly.
Three days before your flight I recommend you call Argentine Airlines and give them your reservation number.
You will not be able to do an online check-in but when you call you will be able to reserve your seat number.
If you are traveling with someone, you will definitely want to make sure you are sitting next to them. If you don't do this you run the risk that the airline will assign you separate seats.
YOU DO NOT NEED A VISA IF YOU ARE A U.S. CITIZEN. YOU WILL BE GRANTED THREE MONTHS. Once you are here you can request an additional 3 month extension a week before your original visa expires, but you will not be granted a 3rd visa. You only get 2 visas (known in Argentina as PROROGAS) per entry. If your visa expires you will not be deported. However, when you decide to leave the country you will be charged a fee.