Never talk about sex to a chick you dont really know. Don't ever start a conversation with a girl with sex, or sexual innuendoes as you just come off as insensitve needy jerk.
If you want to get the relationship going in that direction then use patterns , bodylanguage or indirectly express your desires but never a direct verbal conversation. Seduce her by talking about things that get her in the mood for sex , stir up those feelings and emotions then link them to yourself. Create a connection between the two of you with patterns (eg Blow Job Pattern)
******* PATTERN
Ask her about something she likes to eat and then describe it in a sexual way to get her subconscious thinking about sex.
Her : Lollipops
You :Mmmm....that's yummy. I don't know if you can IMAGINE... SUCKING into one sweet, delicious, juicy lollypop NOW... mmm... can you taste the sweetness of the candy... swishing INSIDE YOUR MOUTH... mmm... soo tasty... doesn't that give you lots of pleasure and ha-PENIS just thinking about that? Mmm... I bet, if there were lollipop here NOW, you'd WANT IT IN YOUR MOUTH
(taken from fastseduction.com)
I've never tried this pattern so it could be bull****. If i really wanna bang a chicks brains out they can usually tell from the tone of my voice and my bodylanguage.