First: know the best ways around (I'd recommend playing before to know, or consulte a guide)
Second: play on average, why? Because nps can have gun and it's easy.
Third: ignore almost all nps, and try to do the fastest way.
Hint: when you need the krotchy doll's, hand over the Garry Coleman book to him (krotchy) and he'll give it to you, saving some minutes.
My first attempt was: 01:29:08, I know, 52 seconds it's tight, but in my defense, it was my first time playing the game for real