Excessive Blinking
If someone blinks a lot, it’s pretty easy to notice. It’s easy to dismiss this as there being something in that person’s eye, but there are other reasons they may be blinking excessively as well. For example, they may be under a lot of stress, and their eye is twitching. Or, the person could be telling a lie, and the nervous blinking is a giveaway.
Blinking a lot could be a sign that someone’s romantically interested in you as well. Combined with the sideways glance, and you may be onto something.