Here is a brief tute on the first part of how to decorate cookies. What I'm starting with is run-out frosting. (the smooth frosting you see underneath all the decorations)
First, make a batch of royal icing (recipe is in the spring cookies thread)
It should look like thick marshmallow cream when beaten.
Make sure you cover the bowl of your mixer with a damp cloth. This frosting air dries and will become crusty within a few minutes.
Next, prepare a frosting bag. I use the Wilton disposable bags with a coupler (not disposable!) and a number three tip. Cut the bag open at the bottom just enough that the large coupler piece will fit through the opening just up to the threads of the screw. Place the tip on the out side of the bag, over the couple. The tip should also fit over the plastic bag. Screw the other end of the couple onto the threads, fold the top of the bag down and tip it into a glass.
Next, scoop out about half a cup of icing (or however much you determine you need for a specific color) and put into a small bowl. Add food coloring. Remember, less is more. If it's too pale you can always darken it up. Too dark, and you waste a lot of icing trying to lighten it up!
Add a few drops of water and mix.
When you are happy with the color, keep adding water in small amounts until the icing becomes fluid enough that it will self-level. Not too much liquid. Just enough that it is still thick, but when you dribble a thread of icing back into the bowl, it will slowly sink into itself and become smooth again.
Carefully pour your icing into the icing bag. A little will leak out the tip, but it won't matter. Unfold the top of the bag and twist it closed above the frosting line. (You don't want to squirt frosting over the top of your bag.) Secure it with a twist tie. A word about filling bags. DON'T overfill your bags. You will exhaust your hands and an over full bag will always ooze out the top.
Place a damp cloth in a large boll with tall enough sides to support your bags. Place your frosting bags TIPS UP in the bowl with your twist-tied bottom in the bowl. Cover the tips that are sticking out the top with another damp cloth. Make as many colors as you need, storing them all as directed as soon as you make them.
I know, all this prep work just to get to this simple instruction. But believe me, it is worth the effort to get this right. It will save you a lot of frustration with crusty, blocked tips and oozing messes. (eew, that sounds awful)
So magically appearing are the cookies you baked off, ready for icing.
Pick a cookie and start an outline with your chosen color. Don't get too close the edge or your run-out will run off! You can use different colors for different flower petals like I have here.
When you've done an outline, fill in the color. This is where you can start to get creative and play. You can even dot another color over a run-out to make smooth polka dots. Just don't wait too long to do it or it won't smooth out. When you get all your run-outs done, wait at least three to four hours in a dry climate and over night if you live in a humid climate for your run-out to be dry enough to take decoration. I'll post another tutorial on some basic decorating tips when I do my next batch of cookies. I hope this helps anyone who has always wanted to do a run-out, but didn't know how. If anyone has a question, please feel free to pm me. There is so much more to say, and I'm sure I've forgotten something. If I have, please forgive the oversight. I'm sure the mods are groaning about the length of this post!