first of all, welcome to Buenos Aires.
Well, i will tell you what you need to know when is time to call an escort.
I dont know how much spanish do you understand, but if you can read expierences posted in the section "mujeres", there you can find people who had sex with different women and there they tell how they enjoyed that time. In case you dont understand spanish, then i can help you.
First of all you have to call the girl to the number written below the photo (it will sure be a private place, where a secretary will talk with you by phone). Commonly, is hard to negotiate the price because they have an official price, but maybe you can arrange a little diference in favour for you.
You have to be aware that some places have a very bad service, and maybe you arrange a meeting with a girl but when you go there the secretary tells you that the girl is not present, so you must choose good places for example: area-vip.
If you want to arrange a meeting in your house you must know that not all girls do that, but the girls who do it ussually go alone, but you have to pay the taxi and a little difference. The condoms are always provided so dont buy it.
if you want to know girls who do great services just tell how's your girl type here and people will answer you.
i dont know good girls in Privados, i like more going to night clubs as pampita (av. figueroa alcorta & la pampa) or madahos (vicente lopez & azcuenaga).
hope hearing your expieriences at argentina soon,
i feel sorry for my bad english haha