(Blogger thinks I spell theatre wrong. I'd stick my tongue out, but I don't think blogger would care.)
Back in my college days, I learned a little acting trick to help bring out emotions. When I first started writing, I realized it worked just as well to bring out emotional responses in characters. It's so simple you're probably already doing it, but I'm going to pass it along anyway.
Grab your favorite pillow and lie down on the floor, Ask yourself what emotional response you're trying to trigger. Let's go with shyness because it's not one we usually think about. Go ahead and walk yourself through the situation you remember, Then figure out what part of your body is feeling the emotional response. It could be your heart, hands, face, stomach... I feel a lot of my emotions in my stomach. The feelings are random for everyone, but when you can place that emotion with a part of your body it's easier to bring back and when you're feeling it, you can more easily show, rather than tell, your readers how your characters feel it.