Most Helpful Guy
Just text him if you're superb shy. If he knows what he's doing. He will ask you out if he genuinely likes you
Most Helpful Girl
I had this problem in high school too. Start small with just a smile and "hey" every time you pass him. Making eye contact helps.
When you start to feel a little more comfortable, plan a few possible things to chat about (casual things) in advance. Then just try to remember he's a (nice) guy who has invited you to talk to him. You're not doing anything wrong or embarrassing; you're just being nice back and being yourself.
He might even approach you first if he's sees you're approachable again from the smiles.
You can do it! :)