Having interviewed hundreds of traditionally published authors over the past decade, I have seen two essential pathways to publication with a traditional publisher.
1) You find a literary agent who wants to represent your work, and that literary agent sells your book to an editor and a publishing house.
2) You self-publish your book and it sells enough copies (10,000+) that it interests an editor or gives evidence to a literary agent to use in selling a subsequent book to an editor.
What other pathways have you heard of that led to a book deal? What are the specific steps a writer takes to make a traditional publisher want to contract with an author?