Writing is probably the single most scary thing for new decorators, but it really doesn't have to be. Here are some writing tips:
Thin down your frosting slightly for writing. You don't need much water- just a few drops will make a difference.
Use a small tip. I use a number 1 or a number 2 tip for writing and very rarely go any bigger. The smaller tips allow you to fit more words on your cookie and allow for better letter definition.
Practice, practice, practice. Get a piece of waxed paper, tape it to your table and just write. Think of it as "frosting therapy". Write your daily gratitude journal entry or a letter to someone that you'll never send... whatever you want! Just practice writing.
Spacing. Another trick with writing is spacing your message correctly. A simple way to do this is by tracing the cookie cutter that you will be using onto waxed paper several times and then practice writing your message until you get a feel for where you need to start and end your words, and the size that your letters should be. After you practice a few times on paper, you'll be ready to write it on a cookie.
That is the end of our piping tutorial. Hopefully now you feel comfortable with your decorating bag and can move on to do some amazing cookies. Good luck, and feel free to come back to the tutorials anytime for a refresher coarse. Happy decorating, and send me pictures of your successes!