Create a Book Proposal:
Find out what publishers want first by going to their business websites, then organize your book ideas into a formal proposal to go with your queries. Publishers typically have their own templates they prefer you to use for proposals, so make sure to follow their directions accurately and get a template from which to work. Your book summary or synopsis is critically important in that it must be clear, concise, and grab the reader's interest,
A couple of good rules to follow: don't brag, read the submissions guidelines very carefully and make sure you provide only what they are asking. Do not send your manuscript if they ask for a query only.
A bit of good advice: read the publisher website material and find a few good quotations to use in your query directly from the agents. If a publisher is looking for historical fiction, don't send a romance novel.
In general, publishers of fiction will ask you for the following:
Word Count of the Manuscript
What Makes Your Book Unique
Intended Market or Audience
Author bio (short)
Author Marketing Plan
Social Media Presence
Publishers of nonfiction will want an abstract (rather than synopsis) and a Table of Contents, a Bibliography, a Foreword, and whether or not you intend to include an Appendix or Appendices.