Mini Sudoku techniques
Most 6×6 grids yield to the same core toolkit as 9×9 — on a smaller stage.
Full house / last missing digit
If a row, column, or 2×3 block already shows five of six digits, the sixth is forced in the only empty cell.
Naked singles
After updating candidates, any cell with exactly one possibility is a safe placement.
Hidden singles
Scan a row, column, or block for a digit: if it can only go in one cell there, place it — even if your notes still show extras (update notes!).
Pointing / line–block
When all candidates for a digit in a block line up in one row or column inside that block, eliminate that digit from the rest of the line outside the block.
Pairs
Two cells in one house sharing exactly two candidates lock those digits — remove them from other cells in that house.
For heavy pattern work on large grids, see 9×9 Sudoku techniques.