There are a number of editorial options when it comes to preparing your book for publication.
Whether your book needs just a light touch – generally just referred to as book proofreading – or a full developmental edit (or somewhere in-between) may depend as much on your budget as the type of book you’ve written, or indeed your proficiency.
Developmental editing can take place during the writing process, with the editor working alongside the author (though not necessarily physically) to craft and hone the book, rather than waiting for the finished manuscript before suggesting changes. The editing process will consider aspects such as narrative flow, plot and character development – and may result in you having to rewrite chapters or whole chunks of your book.
Such a full edit would be less common in self publishing, where the relationship is such that the author retains control of their work, but this approach is nevertheless an option, particularly where the author values such a contribution – and has the budget for it. For authors with a publishing deal, this level of editing would be quite common. The advantage is that you have a sounding board – which can be really useful if you’re stuck, say, or you’re unsure about the direction of your book, or if you need to test out various plot options etc.
Lower down the ladder is copy editing, which is a lighter touch, and doesn’t generally consider plot and character development but instead tackles consistency, repetition (are you using the same descriptions over and over again, for example, or even the same verb?), awkward sentences and howlers, as well as polishing the spelling and grammar and suggesting rewriting sentences where appropriate or necessary.
Finally, basic proofreading will aim to correct any spelling and grammatical mistakes, and spot missing words, and often suffices for many self-published authors at this stage.
For those writers who think they can get away with none of the above, a word of caution: no matter how good you are, it’s very difficult to check your own work. Because you are aware of what you meant to write, your brain often sees that instead of what you’ve actually written. All professionally published authors have their books proofread and edited, no matter how successful they are. They would not dream of skipping this process.