Just be a confident version of yourself..
Open doors for girls, but don't stare at the ground when you do it..
Don't ever mumble.. Speak confidently..
Never look at the ground..
Always make eye contact, even if she doesn't..
etc, etc, etc..
Oh, and be confident around everyone, not just girls, not just crushes.. Hold the door for everyone, speak clearly to everyone, etc.. Be yourself, just be your confident self..