Do make sure items left are appropriate for children to find. The best swaps are the sort of things that you would like to find yourself - something useful or fun!
Ammunition, knives, drugs and alcohol should not be placed in a cache.
Please do not put food or heavily scented items in a cache. Animals have better noses than humans, and in some cases caches have been chewed through and destroyed because of food items in a cache, plus it really is horrible finding everything in a cache coated with a melted sweet - yuck!
The other items found in caches are travels bugs and geocoins which should not be kept but need to move from cache to cache,. You do not have to leave something if all you take is a travel bug/geocoin as you will not be keeping this item.
If you do trade, it's usual to make a not in your cache log - but not essential.