- Identify the publishers who already publish in your area, and with whose books your book would have a dialogue or a body of likely readers.
- go to their website & read the advice for authors - CUP, OUP, Palgrave, Routledge all have this on their sites.
- Download the proposal form. Fill it out. This usually means:
A broad outline of the argument & intellectual field of the book
A chapter plan
A sample chapter
Some presses (eg CUP) will want the whole ms before they will give you a contract.
In that process think about the broader scope of a book from a PhD. Think about why more people may want to read your research; who should read your research; who is your preferred audience?
BTW, no-one should read your book, or anyone else's. You have to craft a proposal, sample chapter, and book that people will want to read.
PhDs tend to be rather inward looking & solipsistic. A book can't be. So you need to think beyond yourself & your research for a book that others will want to read. (I'm talking about scholars here, not thinking of the general reader or trade press, primarily).
Ways to test this: give bits of drafts of chapters as conference papers. See what intrigues other scholars about the ideas & research results you're offering.
When you submit a proposal, it will be read by the commissioning editor for that area of the press. They will approach a couple of people to read your proposal & write a report (I've done 5 this year so far, phew, I'm statring to say no). On the basis of those reports, the editor will refuse, ask you for changes, or give you the go ahead.
Readers will be looking at your central ideas, your chapter plan, the quality of your sample chapter. I always look to see how much an author is engaging with other scholars, but also how far they're going beyond that. I do judge writing style, grammar, expression (please don't use 'incredibly' as an intensifer - my current bugbear). If a proposal is badly written, and the chapter has grammatical errors, I do wonder about the writer's capacity to produce 80,000 words that people will have to buy. But that's just me.
When I've gone through the process, I've always found readers' reports to be very very helpful. Even the reports which contradict each other. Even the really bad one for my first book, which made me wonder whom I'd been spectacularly rude to in real life (I am rarely rude at all, it was a rogue reader). But I have very little ego about my work; I don't take criticism of my scholarship personally - it's always a chance to improve (student evaluations of my teaching is an entirely other matter, how dare they?
).