ok, im a guy so let me try my advice. (try is a key word here, dunno if this will actually help) if a guy is trying to get your attention, generally they will stick around you like glue. for example, if they stop to talk to you specifically on a regular basis, or if they try and keep a conversation going for no reason, or maybe go outta their way to help you with something multiple times.
I'm actually the shy kind of guy, so when I like a girl, I kinda watch them from afar alot, waiting for a good moment to talk to them or something.
hope that helps!