If your story becomes too long for a literary magazine, you may have a book. Here are some resources I have found helpful in thinking through aspects of planning out a book and submitting to agents or publishers.
Book Proposals
The Short Fuse Guide to Book Proposals
Jane Friedman on Book Proposals
How to Define the Target Audience for Your Memoir
Synopsis:
How to Write a Synopsis (Fuse Literary)
Mastering the Dreaded Synopsis (Writer's Digest)
Memoir Synopsis (Louisa Daesay)
Comp Titles
Literature Map enter authors' names to find other authors that the algorithm has deemed "similar".
Agent Search