So you think you have an idea for a non-fiction book that will fly. You colleagues think it's a decent idea. But ask yourself if a publisher thinks it's good enough to give you a nice advance, commission the book, and publish and disseminate it.

Before you've even written your book, you could save your self a lot of heartbreak and late nights by writing a knock-out proposal. A strong proposal can get your past the first fence, but there are no guarantees.

Look anywhere on Google, and you'll find an outline of what editors are looking for. Research shows that there are a general 4 killer questions that any self-respecting publishing house will measure your proposal against.

1. Is there a large enough audience, with money, who are interested in this book?
A book that you're taking to a major publishing house needs to appeal to a broad audience in the HUNDREDS of thousands. You'll need to do your research. If your topic is in the realm of Commodity Trading, find out the number of dealing members on the world's largest exchanges, such as COMEX and NYMEX, and try to estimate the head-count that may be interested in your topic.

Remember, only a fraction of that audience will actually put their money down and buy your book. A publisher needs to sell between 6,000-7,000 copies of your book to make it viable.

2. Would the idea be more effective as a magazine article?
Your manuscript needs to be a beefy 200 pages minimum, in it's published form. When you've put down all your information on your hot topic - it needs to be 100,000 - 200,000 words. If you're shy of that, either do more digging, or accept that it's perhaps more suited to being a one-off article.

3. What's the Unique Selling Proposition of your book?
The overview of your book must be on the first page of your proposal. What's it about? Who is it for? What's in it?

You must stress to the publishing house why your book is somehow different from any of the other books already in print on your topic (if there are any).

Think how you're going to capture the essence of what makes your book different. Is it organised in a new and fresh way from existing books? Are you reaching a new audience?

4. Why should the publisher let you write it?
Are you the most qualified person available to write this book for this editor? This question can be answered by measuring two different credentials. The 'writing ability' credential and the 'expert experience' credential.

You can sell yourself in the 'About the Author' section of your proposal. If you can, you should include:

• Title, Date of Publication, Publisher, ISBN of previous books
• Names of Magazines which have published you
• Clippings of favourable reviews
• Past sales figures

The expert credentials can help to establish your suitability to write on the subject - to show that you are an authority who can reach your intended audience.

The expert credentials can help to establish your suitability to write on the subject - to show that you are an authority who can reach your intended audience.

In actual fact, you don't have to be that much of an expert to appear to be. The don't really need to be in-depth. For instance, one of our contributers wrote a book on LME Metal Trading, when he wasn't an actual metal trader. He did work for a trader, and knew enough about the business to write his book on the subject with sufficient authority.

If you feel you need some expert experience on a subject that you do not yet have - go out and get it. Want to write a book on how to pay your mortgage with sales on eBay? Well, start paying your mortgage by selling stuff on eBay. That kind of experience is what will get publishers on your side.

If you feel you need some expert experience on a subject that you do not yet have - go out and get it. Want to write a book on how to pay your mortgage with sales on eBay? Well, start paying your mortgage by selling stuff on eBay. That kind of experience is what will get publishers on your side.

Individual publishers may also request extra information - you can generally find this on their websites. For instance, Wiley and Sons often put out 'Calls for Book Proposals' in specific areas, and ask for your proposal to include at least:

• A Table of Contents and detailed discussion of the book, its scope and length
• A discussion of the competing books if any and a discussion of how yours is superior
• A sample chapter or two if available
• Your curriculum vitae
• Estimated completion time

With all the above, and covering the 4 killer questions, you should have a good idea of how to improve an existing proposal that was rejected and to understand how your prospective publisher needs to be impressed.