Scan for naked singles first
Scan for hidden singles in each row, column, and box
Use pencil marks for all empty cells
Eliminate candidates from peers after every placement
Check rows, columns, and boxes for missing numbers
Look for naked pairs and naked triples
Look for hidden pairs and hidden triples
Use box-line interactions
Use pointing pairs and claiming pairs
Fill the most constrained cells first
Re-scan the whole grid after each move
Avoid guessing until all logic is exhausted
Practice common patterns to improve speed
Keep candidate notation neat and consistent
Work systematically row by row, column by column, and box by box