When writing, I know I will always get too close to the work and be unable to see it with clear eyes. This can lead to either hating something good, or being enamored with something sub-par. Second opinions are a must, but you have to be sure that opinion is coming from someone who knows what they’re talking about–not just a casual reader (who are good for general opinions) and certainly not a friend or family member (who are good for encouragement). Other writers are great for this kind of thing (writing groups) but when it comes down to CT scanning the final product for cancers and tumors, you need someone with expertise with a scalpel.
What you need is a professional who won’t care about hurting your feelings, and who can point out every little thing that is or may be wrong with your writing, and also help you to fix it.
This is the magic power of an Editor! Someone who can say ‘you use this word way too many times’ or ‘you don’t understand semi-colons’ or ‘this character has blue eyes in one scene and brown eyes in the next’ or even ‘this plot makes zero sense and I don’t understand anyone’s motivations’–all without cringing or worrying for your precious feelings.
If you aren’t fortunate to know such a person, it’s worth it to seek one out when the time comes. Having the kind of attention an editor can give to your writing will drastically increase your chances of success. They aren’t cheap, but boy are they worth it!