Once I sat next to her during the exam, and before the exam started, we had a good convo, one thread after another and I kinda made her laugh. She told me she hasn't been coming to class lately. So, after the exam was over, she left and I thought I won't see her again. Today, I walked into the store to buy a toothpaste, and noticed her. I called her over and asked her to help me choose one particular brand. She was helping me out and then I told her, I think I saw you before. She told me that yah, you sat next to me during the exam. Next, we got into a convo about text, exam, class and then I said I gotta go, I was running late for class. How do I pick her up? I know which store she works at. She is in my class but she never comes, except for taking exams. Any ideas? How do I get her number? What should I tell her, or how should I start the convo next time I see her in the store?

Go to her store to by something. Run into her "accidentally" and start talking about anything. Invite her to something fun, preferably something related to a common interest you discovered. If not, "I might be going to the beach/club/concert this weekend, you want to come?" is usually good. If she says yes, pull out your cell phone, ask for her number, and tell her you'll let her know what the plans are.