
The queen is the most powerful piece and can deliver checkmate easily when supported by the king. The key is to gradually restrict the opponent's king to the edge of the board.
Use your queen to cut off ranks or files, restricting the enemy king
Bring your king closer to help deliver checkmate
Drive the enemy king to the edge of the board
Avoid stalemate by always leaving the enemy king at least one square
Moving the queen too close and getting it captured
Creating stalemate by taking away all enemy king moves
Not activating your king to help