So as far as I remember this is what happened-

Me-Hi, good afternoon sir.

VO-(looking at his computer) Hi, pass me your passport.

me-(Giving passport and some important documents such as I-20, SAT and TOEFL scores and school transcripts) Here you go sir.
VO- So, when did you finish your undergrad?

me-I finished my school in march.

VO-oh ok, what do your parents do?

me-my dad is the***** and my mom is the*****

VO-Alright, do you know anyone in the US?

me-Yes, my sister.

VO-what is she doing?

me-She is currently working for*** in***

VO-(typing something in his computer) Oh, How long has she been in the US for?
me-around 5 to 6 years.

VO-Do you know what VISA is she on?

me-Yes, H-1.
VO-(nods his head typing stuff in his computer)

VO-Sir, it says that you have a Valid B-2 VISA for the US can I have a look?

me-yes sir its in my old passport(Gave him my old passport *my hands were trembling with nervousness but somehow controlled them and passed it to him*)

VO-hmm, so when was the last time you visited the US?

me-In 2011, for my sisters graduation.

VO-Ok your VISA has been approved.

me-Thank you so much!

Note-The key is confidence, its easier said then done but it helped.
My VO was an american chinese guy and was pretty calm.
Though he didn't ask me about which University? why this major? and stuff like that be prepared for it!
As long as i remember it was window no 26.
Hope this helps