Sudoku X shares most of its strategies in common with the main sudoku puzzle; therefore it is well worth reading the section on sudoku strategy for the main raft of hints and tips on solving sudoku X.

Of course, the other restriction with sudoku X over and above standard sudoku is that the cells in each side of the 'X' shape must contain the numbers 1 - 6 or 1 - 9 once and once only.

Therefore you need to bear this in mind as it will be crucial to solving all but the most simple sudoku 'X' puzzles.

The main tactic with sudoku X is simply to play quite a few of them to get used to this fact. Particularly if you started off with standard sudoku like most people do then you 'train' yourself to take into account the vertical, horizontal and 3 x 2 or 3 x 3 boxes, but often forget to consider the diagonal.

By considering the diagonal and therefore having four considerations with each cell that you examine, you can then simply apply all the strategies from standard sudoku to solve sudoku X puzzles. Good luck!