Just crack a smile sometimes.
I know, I know...
Folks nowadays are on that "Ooo...I'm so deep and unique because I don't socialize or smile...Ooo...I'm introverted...Ooo...fukk society...Ooo" edgelord crap but, can't understand why they can't get a friend or a date, especially on the internet (In general, not at you OP). Take it from someone who has been living on the internet for fifteen years and is usually quiet:
CRACKING A SMILE SERIOUSLY WORKS. I have had some really interesting, worthwhile conversations that way and met some cool people who in the long run hooked me up from time to time in life.
If the chick doesn't smile back or gives you a stank attitude, just keep it moving. No need to convince her otherwise; wasting time.
Body language plays a huge role in subtle ways.
Also, your internal belief system. If you believe that no girl wants you or wants to give you the time of day well, that is what you will receive.
So yeah, close mouths don't get fed.
P.S.: Women have been conditioned not to approach and I'll admit it can feel a little odd to have a chick do the approaching and inviting. When a chick does take the initiative, she'll get labeled as desperate or thirsty or even slutty. So, in response, a lot of chicks hold back while giving off flirtatious body language and cues but, a lot of times, guys can be oblivious to that.