Walk up to them and say "Hey handsome." Pick any body part and tell them it is hot. Or you could say that seeing their body drives you wild. Guys don't get complimented as often as women, so anything you say will mean a lot. There is nothing wrong with calling a guy cute.
Well you could always ask him out, or ask him to visit you. he will know then that you like him. Or just say what think of him and ask if he feels the same about you
could just be neutral and call him good looking I personaly would prefer hot or sexy I would take cute, handsome is another option although the others have more of a chance at coming off better (less people take as a complement compared to the others. you could always say he has a good look or style