I don't hide the fact that I own guns but I also don't advertise it. If its someone I know decently well I'm usually pretty open about it and might mention it in the course of a conversation to gauge their interest and/or opinion regarding firearms. I'm relatively open about it at work (Corrections, not around the inmates though for obvious reasons) because everyone knows in part because I am the "gun guy" out of the group that people come to with questions.
As someone else said, though, I don't do NRA stickers or anything on my car or any other property to advertise it. No reason to make myself a target. When I go shooting, I usually end up bringing alot with me so if they neighbors pay attention the might take notice. But, I live in a small town so most people probably wouldn't bat an eye.