in the game against Simon-B, I should have played for the win instead of accepting a draw because of my active rook and bringing the king into the picture by activating it as most of the pieces are off the board...

Targets and taking advantage of them was the basic theme of this lesson...If you create a target or your opponent gives you one, then follow-up by capitalizing on the target to destroy it! Also if there is a weakness in your opponent's camp, try and keep it immobile, fixed, so you can increase the pressure on the weakness while at the same time improving your position.