From Tenchu to Metal Gear Solid to Splinter Cell, the principles of the stealth kill have been laid out as thus:

Don't let the enemy see you. >Don't let the enemy see you. > Oh, for heaven's sake, DON'T let the enemy see you. > You sure the enemy hasn't seen you? Sic him. > Done? Hopefully other enemies haven't seen you, or else it's all over. > Wait, you mean the enemy SAW you? ALERT MODE!!! 99.99... (Stealth Kill Fission Mailed.)

Or, just watch how the Prince does it in this GDC 2007 video of Ubisoft's bringover of Prince of Persia: Rival Swords (The Two Thrones) for the PSP. Comes complete with exact button-mashing tutorials, too, as well as his usual fare of acrobatics that's going to knock Raiden's socks off (And yeah, the vid looks a bit hazy. Maybe GameTrailers was capping it off with a not-really-shakycam or something).