trust in the unconscious

From Mihnea Moldoveanu's Diaminds: Decoding the Mental Habits of Successful Thinkers:

"Behavior does not have to be conscious to be intelligent."

An important lesson I've learned over the past couple years is to trust (and train) your unconscious self.

That bad feeling you have about making a certain decision. The negative vibes you get when you meet a certain someone. 

Why do these things happen? It's not like I willed them consciously into reality. Yet my gut is sharing important information with me: you're making a mistake; this person isn't trustworthy.

Sometimes, though, these gut reflexes are wrong. That decision turns out to be a good one; I was just naturally predisposed to not normally make decisions like that. That person actually ends up being awesome; I'm just naturally inclined to be suspicious of people who look and talk a certain way (me being the asshole that I am). 

The trick I'm slowly learning is to understand why my intuitions act a certain way. Everyone has tendencies and biases; which ones are at play when my body language immediately closes off to new people and new ideas? 

Alternatively, which "warning signs" are not firing when they should be?