I edited each of my books at least ten times; some of those efforts were in collaboration with my wife's assistance. When we were satisfied we sent it off to fresh eyes (paid professional eyes). After that we both went through the near to final draft to affirm changes and even locate more troublesome areas. Once more through the mill and then if I could have afforded it I'd have paid for a substantive edit. [I think that's where the hardest decision comes in; because it's necessary, yet so expensive that if you are self publishing you may or may not have the available funds.] Though personal edits included many discussions, we were both too close to it to catch things.
If you are truly afraid of looking foolish then you may not want to publish. I can think of some traditional published works I've started to read that could fall in that place of making me wonder about the author and publisher. You will definitely want to pay for good editing; it's usually by the word count and difficulty, so you want to make the manuscript as sparse and polished as possible. You want to be absolutely certain you have squashed everything and then be willing to suffer the reality of the hundred plus things fresh eyes will find wrong with the whole.
If you opt-out for the substantive edit; be aware that that usually means that a lot of your favorite baby's are still bulking the manuscript up. In my first novel, finished product, my mother noted that she felt it was a good story outside of those parts of the book that weren't necessary. (Where was 'she' during all those edits.)
Also after all the edits and if you can; get some place like createspace to make a hard copy that you can take a highlighter to and you'll catch quite a number more odd mistakes that no one caught. I found at least twelve per book that way. And be aware that there will be more the readers will find, even if some of them don't appear to be real--critical--errors [Inserts, ' Who cares if you don't know how to spell susurrus?']. (Apparently the spellchecker for this forum doesn't know.) My two published books have at least one embarrassing mistake (not susurrus) each that no one caught during the whole editing process; which is why I suggest that a writer needs to be insensitive to looking foolish to at least one reader (probably more).
Edit::
Oh yes, one more thing. Own your mistakes no matter which way you publish or how many professional edits you get. Most times you will see the final and approve it and it's not helpful to refer people to your editor as the responsible party; since, if you did have an editor, it would be clear at that point that they missed it. It's your work and you own it: wort's and all.