Playing without a queen
Sometimes, players rely too much on the most powerful piece on the board. If I get a sniff that someone plays that way, I'll do everything I can to take the piece. It's surprising how quickly they'll fold when the piece is taken. I'm not referring to an overlooked capture where the queen is taken; we all do that and get justifiably pissed off at ourselves. I'm talking about queen sacrifices for position, trades of queens, or queens sacrificed for two other major pieces.
I think one has to learn to play without a queen in order to develop as a player.