In order to become good friends easily with a girl, first thing is to ensure that you look nice. You can the n look for one mutual friend who can arrange a meet up for the two of you. After introduction be ice to her and allow space to grow fond of each other. You can now ask for her number.
First you want to look nice and give her a good whole hearted compliment and walk away i should know im a girl. But you want to be sure shes with her friends. Just have friendly conversations with her then after a while walk with her to class and just bluntly and friendly ask for her number.... then i think you can handle the rest