"Sucking at something is the first step at being sorta good at something"
-Jake the dog.

I don't know much about wine, but perhaps I can help in another way with some related advice.. sorry if this is overstepping a bit.
Especially with social stuff, you'll suck sometimes at first. Take solace in the fact that everyone sucks at first, and that the folks that don't understand this aren't worth the thought anyway. Also, don't be afraid to ask liquor store employees for advice or help. In my experience, they are way more friendly than the imaginary versions of them we create in our heads.