For me, it is cover, title and tags, since you will probably only be able to read the story full summary after clicking it.
Tags go for my personal tastes, so it doesn't really matter.
The title is surprisingly important, since it is literally the story's name, so it should be somewhat memorable and catchy.
Finally the cover, it is function should be giving a very vague feel of the story, it may be the story's tone, characters, etc. And to be able to attract attention. That is very important.