Roll Your Ass
Okay, okay, so you all know walking makes less noise than running in the game; however, sometimes you just need that extra speed running to get up close to enemies.
Rolling makes your character move at the same speed as running, but at a greatly reduced noise (compared to running). It's not completely quiet as crab walking, but it is not as loud as running across crickety floorboards. The best part: your assassin can change directions while rolling, so roll like Link if you need speed and stealth.