Lately I've been practicing these two things: 1) looking people in the eye and saying "hi" as they walk by. and 2) If you encounter someone that is in the area you want to search, (like in a park, or on a path) or someone comes around after you've already started searching,(like a neighbor spraying weeds on a trail head... yes that just happened to me) just go about your business, catch their eye and tell them you're on a scavenger hunt. (if you want a short conversation) You can say geocaching if you want to have a longer conversation, meaning most people won't know what it is and you need to explain it to them. This of course, wouldn't necessarily apply to a group of teenagers... in that case, I'd come back later.
