I don’t know if you are like me, but I have a great deal of trouble spotting the errors in my own work. I think it is to do with the way I read and by and large I am a speed reader and can get the hang of a page without studying every word and so on.
This makes it so easy to miss the very things I am trying to find, and that is errors, words that are the wrong words, misspelt words, bad sentences and grammar shockers.
I am lucky that I have a proof reader close by, but still, when making the changes and so on it can be difficult for me to make myself slow down and read the passages slowly and see how they flow and read.
I also find that when I am editing I can get ideas for other parts of the book, or other questions about some other passage. This is easier to deal with because I write these additional thoughts and so on down in my notebook for the time when I do a full and comprehensive review against that notebook. It is a vital step because it will have all of those silly little things, like his hair was long and brown in Ch 1 yet in Ch 6 he had blonde or something like that. His favourite jacket somehow changed from a leather one to denim. These are the little bug bears that we all have to go through at some point, the key is to make sure they are all written down as soon as they come into you head.
I know from experience that to wait to write them down “later” will mean that they are lost forever. Trust me on this.
It takes a great deal of discipline to make sure that every one of these thoughts, comments and so on are written down and addressed when editing and proof reading. It may surprise some of you, but today, when going through my 8th draft (and in truth it is probably the fifteenth or some horrible number like that) I found three places where I needed to add a word or sentence to make it flow better and add in something that I had previously missed all of that time.
It happens to us all. Just be gentle on yourself.