Glaze Royal Icing - Apparently, the best icing for sugar cookies. It hardens nicely so you can stack cookies, but doesn't get hard like a rock so you won't hurt your teeth. It's very tasty too and you can add different extracts to change the flavors.
Decorating with Royal Icing: Recipe and Step-by-Step Tutorial
CHEAP DIY FROSTING BAG HOLDER--Use 99 Cent Store popsicle molds to hold icing bags and keep tips from drying out (place a piece of damp sponge or damp paper towel in each cup to keep tips fresh and ready to use.