The Laws of Sudoku

I was seduced into these puzzles a few months ago, and now I divide my meagre residual leisure time between them and crosswords, which makes me an expert.  I’m sure that no-one who reads this blog is unfamiliar with Sudoku, so I won’t patronise you by spelling out the basic concept or the fundamental techniques.  I can, however, share with you a few tips I’ve registered during my (ahem) several hours’ in-depth experience:

1. When all the obvious and less obvious connections have been detected, stare at it for at least twenty-five minutes.  Then do the quick crossword.  Then stare some more.  Then go and get a drink.
2. The drink will have the immediate effect of revealing the bleedingly obvious link your eyes had meticulously swerved around throughout the pre-drink epoch.  Also the fact that you had written ‘4’ twice in the same nine-by-nine box.
3. I always print it out from the Garduain website, for two reasons: a) there’s just about room on an A4 for the demented aides memoires I need as a memory surrogate; and b) erasers don’t work more than twice on newsprint.  (Actually, my confidence levels have risen to the point where I can start with ink rather than pencil, safe in the knowledge that I can always screw it up, screw it up, and print it again.  It’s surprising how differently take 2 can turn out.) 
4. When the impossible has been eliminated, whatever remains must be, er, equally impossible.  Guesswork should not be resorted to – but occasionally pays off.  Only today, I had to downgrade a ‘hard’ Guranaid Sudoku from ‘impossible’ back to merely ‘hard’ as a result of an inspired guess, which turned out to be wrong but unveiled the (rather subtle) right approach.
5. As an alternative to breaking down into uncontrollable metaphorical sobs, if it’s at all feasible, ask Z.  This never fails.