Techniques used in this Sudoku:

1. Box Row Column (see Easy Sudoku)
2. Triangulation (see Easy Sudoku)
3. Notes (see Medium Sudoku)
4. Obvious Singles (see Easy Sudoku)
5. Hidden Singles (see Expert Sudoku)
6. Obvious Pairs (see Expert Sudoku)

This is the strategy we will use:

1. We start with Box Row Column and Triangulation.
2. No solutions? Write Notes and look for Obvious Singles, Hidden Singles or Obvious Pairs.
3. No solutions? Go back to step 1.