Creating a Book Proposal
Find out what publishers want first by going to their websites. 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.
Read the publisher website material and find a few good quotations from their website to use in your query directly from the publisher or editors. 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.
There are a score of independent presses out there for which you do not need an agent to query. Do not give up on a good project. It takes time and persistence.