best i can say is don't do it in obvious places, if your going to smoke out in public, smoke a joint, something that looks like a ciggarette etc, pipes and bongs stick out.
to hide your stash, personally, i use an empty pack of eclipse mints, can be kept out in open in cars and such doesn't get noticed at all. and i'm pretty sure there air tight but they do cover the smell.
about all i know.