As a girl, give her three pieces of roses then ask her immediately, "do you like me?" If she says yes, then kiss her right away..But if she says no, get the flowers back, kiss her immediately then run!...she can't slap you since she's startled, at least you kissed her... she won't forget you for the rest of her life..That would be fun!

If you really love the girl, fight for it and don't give up! :)

ignore her for a while, you will see, hah

It depends what the situation between you both is and what kind of girl she is. If you have a reasonable connection with her (she knows you and you spend any time together), the common advice of testing her by ignoring her might work. Don't be mean or rude about it. Just be a little more distant and not so keen, to test if she wants to be around you. It could work. Or it might be simpler just to reach out to her and try to know her more closely if she is just a nice and kind girl. You could even try this and then the other if it doesn't work. On the other hand, if you don't have any clear connection with her (like you look on her from afar and wish, but you don't know each other), ignoring her is going to leave you as distant as ever. In that case you need to politely get to know her and establish a connection with her. These are my thoughts and feelings about it. I do not know either of you and I am not an expert.

To Blitzy: What if he likes a girl you like, too. Are you going to suggest the same to him? I agree with Zoeyever. :)