Store at room temperature in a sealed container for up to a month.

TIPS:
Icing must be at the correct consistency. I found that I needed to thin this icing slightly. For outlining thin just slightly, remove about ¼ of the icing and set aside, then continue adding water until you reach the correct consistency for flooding. You'll want the icing that you use to outline the design to be slightly thicker than the icing you use for flooding. Since I'm new to decorating I like to use a #3 or #4 tip for decorating.

I found this tip online at sweetopia.com.: The trick to make sure icing is just right for flooding is called the "10 Second Rule". Drag a butter knife through the surface of your royal icing and count to 10. If the icing surface becomes smooth anywhere between 5 to 10 seconds, then your icing is ready to use. If it takes longer than approximately 10 seconds, the icing is too thick. Slowly add water, a teaspoon at a time. If your icing surface smooths over in less than 5 to 10 seconds, it is too runny. Mix your icing longer and slowly add in more soften confectioner's sugar to thicken.

If you are like me and don't have a steady hand, rest your elbow on something steady. Also, put your pan of cookies on top of a a few books or container to raise them up to a comfortable level for decorating.