if approaching in public i think it’s better to offer your number. some women feel uncomfortable saying no, this way they can accept your number and then the ball is in their court whether or not they want to do anything with it. easy formula is to start with a compliment or question, small talk for a little bit, say it was nice talking to her and ask if you can give her your number if she’d be interested in going out some time
Romantic: “Hey, I think you’re really pretty and would like to take you out sometime. Can I give you my number?” Friendly: start a conversation and finish off with “I think you’re pretty chill, you wanna hang out sometime? Just as friends though” You say they’re pretty only because you know nothing about them, this is assuming that you’re approaching a stranger.