I also ended up making cookies for all the kids in my son's Sunday school class. Cookies are a great way to practice piping skills. I also played around with sprinkles and colored sugar to see what the effect would be.
I outlined the cookies with royal icing and allowed it to set up a few minutes before flooding the cookies with thinned icing. I used the sprinkles and colored sugars while still wet. I allowed them to dry for about 24 hours before doing any additional decorating. I then let all the cookies dry for another 24 hours before placing them in bags.
When doing the lettering or lines a damp art brush can be used to move the line or flatten peaks if your piping doesn't come out perfectly. I'm not always great at remembering to do that, but it does work really well.
1/4 c. meringue powder
1/3 c. water
1 lb. confectioner's sugar
Beat on medium speed 5-7 minutes until still peaks form.
I added a small amount of vanilla to the royal icing to give it some flavor. Additional water can be added in very small amounts (a few drops at a time) to thin enough to flood the cookies.
There are probably better tasting royal recipes out there, but this one is very simple.