Gather near the site just before 11. Dress in your 'shopping' clothes, DO NOT look like a geocacher! Do not interact too much with all other cachers, although you may have arrived with your family or one or two friends for shopping, coffees, or lunch of course. Pretend not to know the other groups of cachers.
At 11:00 a whistle will sound. That is the sign to take out your real or fake (you can cut one from cardboard or thick paper) magnifying glass and search the whole square meticulously - the bricks on the floor and in the low walls, the trees, the fences, the information signs, the lettering on the floor, the statues, each other - search, search, search and then search some more.
At 11:05 another whistle will sound (believe me, this will seem like ages) and we can catch up with each other for the usual banter, signing the logbook, exchanging and discovering travel bugs. We can stay chatting in the square after 11:30 (the official end of the event) and / or we can team up in smaller groups to have a coffee, lunch or tackle some of the nearby caches.