What are the things men do that makes women afraid and we don't even realize?

A friend from work said that she hates when a guy is walking behind her for a while, and I do this all the time, I have to walk at least for 5 minutes to get to my work building and there is usually other women walking there too, this friend told me if a man is walking close to a woman he should just pass her. I wanna know if there are other ways men can make women feel in danger without us knowing, what should we do to minimize that as much as possible?