Very small tip if you want to ask a girl out or for her number. Don't ask, make it sort of a closed statement. Be like, "Hey listen, I gotta get going but it was nice to see you. Why don't I get your number so we can meet again?" Notice the second sentence it is hard to say no. Also you might want to give her a list of possible activities for the next time you meet. For instance she might not like coffee particularly so say, "We could go for some coffee, grab a bite or just chill out in the park." I think I learnt this from Susan Bratton or some name like that