Sometimes after I win a match, and especially if it was a tough match to win, I like to give a compliment on things I thought they're really good at and suggest a reason as to why I think I won. eg. "GG bro! I was really impressed by the power and accuracy of your shots. I put a lot of my focus into 50/50s and closing up space, but if you can work on creating more space for yourself it might help in other matches."

A lot of the time I get messages back telling me how they've had bad luck the last few matches and they were losing motivation, but the encouragement helps get them back in the game. It's a small thing you can do to be helpful towards the community