All I can recommend is look up on YouTube as there are plenty of videos showing shortcuts and stuff. If you're not that good at the game, I wouldn't recommend the world record runs as they require a decent degree of skill to pull off. Stick to videos that show things you're comfortable performing in game.
I do know that when you have to wait for an elevator while the timer is still going off, pause the game a wait a good 2 or 3 minutes and when you unpause, the elevator should open immediately, saving you a few precious seconds. Why should you be punished during a time trial just because the game needs to load?