One of these is queries.
A Killer Query must knock an agent's socks off. A Killer Query must grab your potential agent in a combination of voice, clarity, and focus. A Killer Query must relate to your agent the voice of your story, that is, the unique style that is your writing. A Killer Query must WOW an agent.
All this fuss for a query, you say?
YES!
A query is an essential element to the writer's workshop. A manuscript without a query is like a sandwich without the cheese. It's still good, but the cheese makes it fantastic. (Or bacon, if you prefer.)
A query gives an agent insight to who you are as an author. It portrays the voice and plotting strength of a writer, and gives a hint as to your writing style.
Don't be fooled. Queries are not easy. As a matter of fact, they can be downright evil. A query must convey to your potential agent, editor, publisher the full substance of your story without feeling like a lecture, or sounding like a complete waste of time. A query must be clear, concise, focused, and interesting. It must convey the entire plot of the story... in less than a page of writing.
I am in the process of crafting a query for my two WIP's; The Key Keeper, and Whisper Mansion. It is an interesting new view of the writing world. I've never seen it from this side before, and it's a challenge!
For information on how to craft a query, check out Nathan Bransford's advice:
http://blog.nathanbransford.com/search/label/Anatomy%20of%20a%20Good%20Query%20Letter