Notes on this puzzle
32 digits are printed in this grid and the other 49 cells are yours to fill. A solver that never guesses gets through it in 49 steps.
Most cells fall to the hidden single move: 46 of the 49 steps. Single candidate accounts for 3 more.
Among the givens, 3 is the most common digit (6 times) and 9 the rarest (2). The emptiest box is the top-middle one, with 1 given; the central box is the most crowded, with 8.
Where to beginLook at row 1, column 1 first: a hidden single is available there from the very start. When scanning stalls, look for a cell whose row, column and box together rule out eight digits.