You can't expect shy people to share with you or come directly to talk to you. They will rather see you across the room. They will not maintain eye contact even then.
If they are behaving awkwardly when you are around them, like giggling without talking, then it means they are into you but can't express it.
When they talk to someone they like, shy people usually stammer or get nervous. Although it may surprise you, they can't help it.
People who are shy usually can't talk to the people they like in person, but they are more active online. You will see them flirting a lot online.
When it comes to talking about themselves, shy people usually feel uncomfortable. They'll keep the conversation going by asking you about things.
It may be awkward for them to open up if he accidentally touches you on the shoulder or on the hand. So consider it a sign.
Shy people surely can't open up about their feelings when around you when sober, but they will open up when drinking.