So far my posts haven't really distinguished between fiction and non-fiction, but there are some things you could do differently if you are submitting a non-fiction text. You can, of course, simply send in the first three chapters and a synopsis – but there is scope for much more.
Whereas for fiction, less is more, non-fiction lends itself to a lot more variety. Firstly, though, what doesn't change? Still send in the first three sequential chapters (double-spaced) as the editor needs to know how your style flows from subject to subject. You will also still need a synopsis – this can be a bit more detailed but don't make it more than about two pages, single spaced.
Your experience becomes much more relevant, especially if you are writing with a degree of expertise, so in your covering letter include any relevant qualifications or work experience (what agent Judy Chilcote refers to as 'credentials'). You could also send a CV (not needed for most fiction submissions), any press coverage your idea or group has had, and relevant screen shots from web pages you may have up.
If you are doing a website to link to your submission, don't make the mistake I made with mine initially, where I forgot to put any contact details on it! You need to remember that any supporting material for your submission should also be checked for spelling and grammatical errors, so only include what you are confident about.
If your idea needs illustration – drawings, diagrams or photographs – feel free to include them. Consider teaming up with an artistic friend if this is not your area of expertise, but err on the side of simplicity. You are trying to give the editor an idea of what the finished book could look like, not a completed project.
It is more common for work to be taken on before completion when it comes to non-fiction, but publishers are wary of 'great ideas' that require an advance upfront to be completed. Trust me, if there were an expenses fund for a book like 'Interviews With Great Cocktail Makers of the Caribbean', the person reading your manuscript would already have applied!
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