I found this blog post interesting because it starts out with a simple premise: you are not as "approachable" as you think.
It also introduces the concept of "Daily Five Minutes". That article is pretty long, but this post sums it up rather nicely:
Very briefly, the D5M is a simple habit. Each day, without fail, managers are to give five minutes of no-agenda time to at least one of their employees.
Your time is one of the most precious resources you have, and to give it as a gift to someone in the form of the Daily Five Minutes® just may be one of the best work-expressions of unconditional aloha there is.
There are also several sets of questions that can be involved (read "Daily Five Minutes" for the full thing) but the idea is simple and powerful. I intend to give it a try.
Do you already do this?