I dont really know how hard this would be to do, but add somekind of chatsystem e.g. like irc channels.
Since you daily see alot of high div players in TF2Center,all the new players could ask hints/tips how to play certain class.
It could be done also by having some sort of Q/A Inbox.
These "Mentors" would be selected and they would be easy to acces in front page of tf2center lobbies.
I know this is kind of badly described, but as in harsh example:
I could be sniper mentor,so my name and class would be there easily to see.
Then new players who want to learn about sniper clicks my name and gets into to the Q/A section.
Personally i would answer to questions when waiting for lobby to fill up and it would eventually even raise the general skill
of tf2center.