How to catch a guys eye?

Wait for it to fall out

Try to catch their eyes a few times, but not like a random staring person.A nd smile when you make eye contact, like 'oh, I didn't know I was looking in your direction', and then talk to them after this has happened a few times. If you catch them looking at you back, it's a good indication that they're interested.

Wait till he throughs it

Just go to him talk to him casually with your best outfit(boys never say no talking to a girl), and while talking don't hesitate(important) and from your next meeting ignore him, i think you'll have better results.

Wear clothes that show off a lot of skin .... Like a tank top of mini skirt
not saying you should be a slutty and stuff xD LOL
but in the "science" world. Showing off skin does attract men :D ~ good luck hun  !