How to write the dragon's calligraphy backwards?

You mean the traditional Chinese characters of dragon.

There are many ways to write it, depending on whether you want regular script, running script or other scripts.

The following is for your reference:

I guess you are a calligraphy lover. Choosing a good brush is actually very important. You can find this article to read Top Ten Brush Brands in China (with brush selection and maintenance methods). This paper introduces some easy-to-write brushes and how to choose and maintain them. I hope it helps you ~