A follow-up to the earlier tip: Don’t be where they saw you last
This tactic applies to more than just traffic stops. When I knock on a door, whether for a warrant attempt or a civil process, I watch the windows and/or peepholes. If I see someone look out I always move to a different location so that when they open the door, I won’t still be standing where they saw me last.
Also, when I return to my patrol car I always leave the area before doing any paperwork.