Do not stare. Staring at him/her won't do anything. They or someone else could catch you in the act. If possible, stop your habit of staring at them. Or, just make sure no one (including them!) is watching, and just quickly side-glance at them.
Avoid telling anyone that you have a crush on this person. Especially someone with a reputation for being a gossip/big mouth and untrustworthy. If you don't feel one hundred percent sure someone won't use it against you, don't tell. You never know when you will fight with someone. They might use blackmail. You don't want it.
Treat your crush exactly the same way as you treat all your acquaintances. Be polite, but not overly attentive. If you tag along with them too much, they'll be annoyed or someone else will find out that you like him/her! But then again, you don't want to be too shy around them, either. They might consider you weird or be suspicious.
Be yourself. If your special someone ends up liking you, you want them to fall for who you really are, not someone you pretended to be.
Keep a diary. This might be a good way to tell someone you've got a crush on someone, without letting anyone know. (Except if someone reads it.) If you are embarrassed about your crush, this can be a good way of looking at it objectively.
Do not giggle hysterically when he/she looks over at you. They'll think you're creepy.
how about i fall a crush wif someone
its will always be my secret :)