Sometimes a Sith Lord must be extremely silent and undedected to be effective in the field. Other than long years of experience, there are some basic teachniques to being stealthy:
-Remove yourself from the group. More importantly, remove yourself from the group mentality. Do this by observing the group not as individuals but as a single entity.
-Be aware of the shadows and the light; areas of cover. Feel the shadows pull you in, and feel as the entity looses its sight and tuning into of you.
-You've done it.
This isn't special or anything other than the fact that it puts you into a predatory mode. And as we all know, the big cats are not seen by thier prey until it is too late.