Great question. The art tags are more important... Writing, Art, Photography, Poetry...
Make sure you put the relevant ones and then add the subject matter.
There may be some cases where you create something that directly ties to another main topic. For example I wrote a "Love Poem To Steemit" and I put Steemit as the top topic, but still had poetry and writing.
I would stick with the broadest terms first and your last one should be the most narrow.
I hope that helps. I might do a blog just on tags. Thanks for the idea.