How to seem more approachable?

According to a lot of people, I’m not really approachable, and they are usually “intimidated” by me.

Truth is, I don’t see why. I’m completely shy, but I’m really nice.
Some people say that I should smile more to look more approachable, but I’m not going to smile as I’m reading a book or something. That is just creepy.
What I’ve worked on so far, is standing WITHOUT crossing my arms.

Any other tips?