It is generally thought to be unwise to bring the queen out too early. The cluttered board makes her more vulnerable to entrapment.

Guard the king closely. His loss means loss of the game. He is typically not a good piece to use on offense, but will be a help in a carefully constructed defense.

Castling is a great aid in defensive strategy. It also has a tendency to bring a powerful rook into play when under normal circumstances it might be stuck behind a wall of pawns.