http://www.artofwarsuntzu.com/Art%20of%20War%20PDF.pdf < PDF for it if you've never heard of it.
The Art of War is one of the most famous military manuals of all time, still used today, and written by the genius Taoist and General named Sun Tzu.
It's basically a list of ideas for war, and they're easily applyable to a lot of competitive scenarios, such as yugioh.
Choice phrases for yugioh;
Attack him where he is unprepared, appear where you are not expected.
Standing on the defensive indicates insufficient strength; attacking, a superabundance of strength.
When invading hostile territory, the general principle is, that penetrating deeply brings
cohesion; penetrating but a short way means dispersion.
A lot of them apply to the aspects of playing conservatively/aggro in yugioh, which is a playstyle difference that, in my opinion, primarily defines competitive yugioh.
Thoughts? Some discussion about these ideas would be pretty neato.