Yes I know it is only August, but with three young children I need to be prepared for December.
I have an Advent Calendar with little drawers in (home made) and put things in for each day - activities, coins and/or sweets.
I have seen some wonderful suggestions on other threads, but thought it might be helpful to have a dedicated thread for this.
Two things I have learned is to 1) put activities in the night before, not all at the beginning, as they are very much dependent on weather, time available, energy levels etc, and 2) do not put sweets in until the night before otherwise they disappear 