Compliment and Congradulate them
This is also something that seems really small, but can help more than many might realize. If you want to talk to someone and are not sure how to go about it, find something that you like about them and compliment them on it! They could be trying something new so the positive feedback could really help them with some confidence. Or maybe they had just won a really close game the other night. It can be nice to feel recognized for your hard work.