How to talk to girls that you don’t see on a regular basis

So, let’s suppose you see a girl once, or rarely, that you really like, such as on campus in college, part of some campus club that meets rarely, or something along the lines of that.

What’s the best approach when it comes to dating her (the end goal is for her to be my girlfriend)?

Should I attempt to complement and or converse with her for a while, and if there appears to be a good vibe, ask for her phone number and ask her out (on a date)?

Or, should I try to find some way to get her to want to be friends with me, and take things slowly from there?

I’ve tried it once with a girl at some college club where we only meetup once a month. I talked to her (things seemed to be going well), and got her phone number. She ignored my texts however when I tried texting her, and a second time meeting in person, she also seemed to have a casual conversation (less exciting than the first time) with me with no issues. Third time seeing her in person, she seemed to not want to be around me, and our conversation was very short. She also did not want to give out her social media to me when I asked her.

I sort of blame that situation on having enough opportunities to see her and interact with her, as well as the fact that my approach was too “quick” for her.

The “friends first” approach in this situation may have been the way to go, but I’m not sure what I should do to get her to like me like that, given the few opportunities I would’ve had.

So for all the girls on this subreddit, how would you feel being approached by some guy you will never see again, or rarely, enjoying a conversation with him, and him asking you for your phone number and a time to meetup?

Would you want a slower approach instead, like him inviting you to some group event, or intending to be friends with you first?

I’m thinking more of a college campus setting here, but it can be anywhere.

Thanks for any advice in advance!