I think also smiling and a friendly but brief explanation when asked is a good idea, had someone come out of his garden gate and ask what I was doing as I crawled into a gap in some bushed to remove a cache the other day. Not surprised that he was a little worried at spotting someone crawling around outside his propertY. I just told him I was doing a kind of treasure hunt and he was fine, wished me a good day and went back inside. Maybe I'm not the most inconspicuous of geocachers either. Perhaps we will start to look less suspicious with experience