Should I smile at my crush? pls help?

okay so my crush always looks at me when i enter the room, but he doesn't smile. i look at him sometimes but i don't smile because he doesn't. so i look away quickly. lol i don't know why he does this. he is the only person at my job who does this. and sometimes when i am talking to his friends he stares at me when i am not looking. so should i turn to him and smile at him? i am so shy around him. so what should i do? help!!