A better first move
Small habits that make a new puzzle feel less intimidating.
Scan before you write.
Pick a digit that appears several times in the grid. Follow its rows and columns through neighboring boxes. Those existing digits often rule out most possible positions in another box.
Work on the fullest unit.
A row missing two numbers is easier to inspect than a row missing seven. Compare the two empty cells with their columns and boxes. If one of the missing digits cannot fit in a cell, it belongs in the other.
Keep possibilities separate from answers.
Use Notes for candidates and normal entry for deductions. Guessing a large number makes later reasoning depend on an unproven step. If you are unsure, leave a note and look elsewhere.
Change your perspective.
If scanning rows has stopped helping, scan boxes or follow a single digit around the grid. A hidden single means only one cell in a unit accepts a particular digit, even if that cell still has several candidates.
Use a hint to learn the pattern.
Read the explanation and find the highlighted cells before applying the move. The point is to recognize the same idea the next time it appears. Taking a break also helps: your current game is saved on this browser when local storage is available.