Try for a middle ground between “just going for someone” and playing hard to get.
If you let your strong feelings for a guy completely control the way you act towards him, it may seem to him that you won’t care how well he treats you. By the law of averages, the guys you are most interested in will tend to be less interested in you at first, so give them a chance to get to know you a bit and show that they like you back.
On the other hand, completely hiding the way that you feel about someone won’t work. In order for someone to really like you, you have to be honest in the way that you present yourself.