Look, look away and pretend.

The best tip that will drive the guy crazy is, you look at him acouple of times and bit longer. hen maybe the next day you pretend that you don't see him when you maybe pass him in the hall with you friends, and make sure you giggle or laugh with you friends, than the next day you look at him maybe oce or twice but jus amke sure that he catches you eye then look away.

that's my best tip and trust me it work , it works for me everytime. And maybe if you twirl you hair or something will help or bite you bottom lip gently.