Your king sits on the back rank when the queens come off
Middlegame instinct says hide the king. Once queens trade, that instinct loses you games. The endgame king is a fighting piece. March it to the centre.
vs game: a level rook endgame, white centralised the king, black left his on g8. Lost the endgame by tempo.
vs game: a pawn endgame, the side with the more active king walked through the position.