Be alert at all times for alignments between your opponent's pieces (as well as your own). A look at Black’s position here turns up a few of them, the subtlest and most interesting of which is the alignment of Black’s king and his rook—which is loose. The pieces are on a dark-squared diagonal, and White easily can get his dark-squared bishop to g3; so the possibility of a skewer comes into view. The pawn on e5 is the only impediment, and so must be cleared away. How? Again, with a standard capture of a piece it protects: White plays NxN, and if Black recaptures with e5xN, White has the skewer Bg3+. He then wins the rook after Black’s king moves.