If you are going to flirt with your crush in person, you have to make sure that you will do it properly. You do not want your crush to feel scared because you are coming on too strong. You have to be subtle but still respectful at the same time. You can give a compliment at the right time. It will be enough to flatter your crush and make her blush. You can also say some jokes that will make her laugh.
It is likely that she will remember you because of your sense of humor. She will also think that you are fun to be with and will like you for it. When you become close with your crush, that is when you can start becoming more flirtatious.