for not shy guys... they will stare at you a lot whether that's your face or your body or they may do the same things that guys do they start at the face and examine down, some girls play with their hair or smile a lot when they see you... guys do that as well. if she's a shy girl.. some will blush and go red, some will look down at the floor or another direction when you walk past them.. they won't make eye contact with you... some giggle a lot in your presence.. like you can tell when she giggling more than usual
Smiling a lot, for sure. Holding her attention on you (and not gazing around the rest of the room or playing with her phone, etc.) Touching you, like reaching out to graze your shoulder or hand, is also a great sign. Women simply don't touch men that they don't like.
if you catch her looking at you when you're not looking at her, she smiles a lot, bites her lip, plays with her hair and if her eyes wander away from your face to the rest of you.
She laughs at almost everything you say, when you talk to her, her face lights up and she is interested in what you have to say. If she's shy, and you say something that's not that funny but she laughs really loud, it might be a hint that she likes you and thinks you're cute!
She doesn't ignore what you say, she responds to every question or comment you speak out. She's almost always in a good mood when you're around.