The challenge is to think clearheadedly about the mating elements you have in place and the elements you need to create. You have diagonal pressure against h8, and it’s the good kind; your bishop is on f6, so Black won’t be able to interpose a pawn in its way. And the g-file already is open, an invitation to some form of Morphy’s mate. Lastly you have two heavy pieces out on the board, so look for a way to get one of them onto the g-file. The constraints are Black’s rook on e4 and his queen on c7, both of which guard squares you want. If you start with RxR you solve nothing; Black’s rooks are doubled, so he replies RxR and now your resources for taking control of the g-file have been reduced by a piece with no relevant change in Black’s position. So experiment with the queen. If it moves to g3, Black has QxQ and your threat is over. If it moves to g4, Black’s forced reply is RxQ—but then you have RxR+, and now your rook drives down the g-file with nothing attacking it. The next diagram continues the sequence.