I strongly suggest to ALWAYS use outside editors, cost not withstanding (If cost is an issue, I believe in the old payment plan method). The question often arises...Should I hire an editor or edit my book on my own? What do "most" self-published authors do? Usually, due to monetary constraints, they try their best to do the edit on their own.
I firmly believe that we cannot catch our own mistakes for the most part because we tend to read only what we "intended" to write. Outside editors don't have that same filter in place. When we edit our own work, the errors that slip through are the ones that help label self-published work as inferior to that of traditional publishers.
I found this to be true recently and thought I`d share it with all of you. Since I`m an editor, I could not help it, but it is sound advice.
What article would be complete without my link? So here it is...
http://www.authorsden.com/visit/author.asp?id=150139