The most important element in designing a GridTemplate, is making sure that the DayValues you choose for your tokens will be the ones expected by Q++Studio. This is particularly true for monthly grids.
The second most important element is to decide which visual elements of the grid will be deleted on days outside the month (assuming you set that property to Hide).
The remainder of monthly grid design consists of looking at other people's grids to learn by example, knowing a few of the tricks, and avoiding the common traps. These are discussed in making sure an object is never deleted, no matter what happens and i do not want to hide outside days, i want to diplay them differently.