I am planning to hit on a girl 1 in our school, but girl 2 got came to our group, I ask my friend her name and I told her:

Hey Girl 2 name, you're cute, let's go to the mall.

At first she told me I'm crazy. She blushed, and probably got shocked as I don't know her. I ignore her after that, my group also thought I was joking. One of my girl friends ask if I'm serious, I said yes why would I ask if I'm not. Then the cute girl can't believe and keep asking me if I'm serious. She said she have exams and she don't go out much. I said Ok then no, she immediately responded We can go out on Friday, and I said ok sure.

This is my first attempt in PUA. Earlier in the morning I sat next to a nice looking girl but I can't say anything, devastated, then my real target is with a group, I don't know how to get to her. I don't want to get excited because I can't believe the girl 2 agreed, but shit whatever man. I also kept acting cool about it.

I observed that, I don't look that sincere, probably it's because I act cool, or like I don't care if she say yes or no, I just really don't want to care if she reject me.
Also, is it ok to say those stuff in a group? I think I just revealed a part of PUA to them. I don't to stay very long, just enough to do some things with her. Girl 1 is still my target. Also, I'm in a small school, which probably in my opinion, things I do will spread like wildfire, if I continue it.

What aspect should I work on?