Notes on this puzzle
Sudoku #5206 is a medium grid with 30 givens, which leaves 51 cells waiting for a digit. Played purely by logic, it takes 51 forced steps from the first placement to the last.
Most cells fall to the hidden single move: 49 of the 51 steps. Single candidate accounts for 2 more.
Among the givens, 4 is the most common digit (5 times) and 6 the rarest (1). The emptiest box is the top-middle one, with 3 givens; the top-left box is the most crowded, with 4.
Where to beginLook at row 3, column 6 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.