Sprinkling cakes with icing sugar
Icing sugar is lovely as it covers a magnitude of faults in cakes - I should know. But it is really troublesome stuff as it tends to cover the whole kitchen in a cloud of dust.
Contain the icing sugar
I usually use a little tea strainer to sprinkle it evenly over a cake. An even better idea: re-use a spice container with small holes in the cap, washed and dried very well.
To sprinkle small cakes and biscuits, mince pies for instance (although the picture below shows otherwise!), keep them on the wire rack and set it over the sink. Get someone to hold it for you or place it at the bottom of dry sink. The mess will be avoided but make sure the water doesn't suddenly start running!