Whether she has a man or not should be indifferent to you.. if she DOES have a boyfriend the only way she will leave him for you is if you come across as more alpha. Would an alpha care if his target has a girlfriend or not? No, he would game her as usual and if she is not receptive he would move along because whats it to him??.. he has puzzy swooning for him left and right and one chick will never make or break him. That is the attitude you must convey.
Being better looking is not necessary but of course can never hurt you're cause. Good luck my man.