My most important tip on playground etiquette is respect. A lot of times, we think politeness means forcing children to share, but if we respect our children as people and allow them to make decisions about what of theirs they would like to share, and also what other would like to share; that's actually much more polite in the end. If we make our children give toys that they don't want to give, that's not really teaching them about possessions. And if we allow them to take other toys from another child that they don't want to give up on their own, then that's not really teaching them anything about etiquette at all. Respect is always the most important thing.