Publishing attracts a lot of encouraging language. Here is the part that usually goes unsaid until after the invoice.

• Your book will not be stocked in bookshops. Print-on-demand titles can be ordered by any shop in the country, and that is a real and useful thing. It is not the same as sitting on a table in Waterstones, and anyone who implies otherwise is selling you something.
• We cannot make your book sell. Most debut novels sell in the low hundreds at best. We will produce a book you are proud of and put it everywhere it can be bought. What happens next is not something any publisher can promise.
• We do not edit. We are designers and publishers, not editors. If your manuscript needs editorial work we will say so and point you to independent editors — and we take no commission from them, so the recommendation is honest.
• We turn manuscripts down. Not every book is one we can produce well or want our imprint on. We publish our acceptance rate every year so you can see that the standard is real.
• Leaving costs you something. You can go at any time on ninety days’ notice with every file. But the book would need republishing under a new ISBN, and an Amazon listing does not carry its reviews or its ranking across. You should know that before you sign, not after.