Editors, crit partners, beta readers...they all amount to the same thing: Someone who is going to rake over your manuscript, chop it up, mark it in red and throw it back to you with an email saying "Great job! Here are the billionity things I would fix!"
Are you ready for it? Can you handle it?
Authors shoot themselves in the respective feet by being too afraid to let an editor touch their work. Some don't want their words changed. Others have low self-esteem when it comes to their writing and don't think they could handle any blows. But if you won't let a beta reader take a look, how are you going to get an agent or publisher to take a look?
Here's an industry secret: Your first manuscript needs to be pretty damn perfect (unless you're very lucky) for anyone to even glance at it twice. Use the wrong its on the first page or use a sentence structure that goes off on tangents without backing up the original idea, and you're headed for the reject pile.
After that, you're golden. The more books you get out there, the less awesome they have to be. It gets to a point when you just have to type random words on a page that amount to nothing and you're just blindly accepted. Someone else gets to do the work of making it make sense and flow both grammatically and content-wise. (I'm not at that point yet, but I know a guy who knows a guy.)
Point being, as you agonize over the logical strength of your second paragraph, and you feel defeated because you have 45,000 more words to sift through that you thought you got right the first time, take heart. Do it well now, and you won't have to do it for long.
You only need to achieve perfection once (or just a few times). After that, they pay someone else to achieve it for you / help you achieve it.
So, how do you take that first step then? How do you find the right voice to edit your piece? Here's some advice.
1) Friends. Friends are tricky. If you're a writer, you probably have some fairly literate friends. They probably like to read. Use them. Ask them first. Anyone interested will let you know. But be wary. If you are the sensitive type, and you choose a blunt friend to look at your piece, you may get your feelings hurt. Editing ruins friendships. Before you embark on an editor / writer relationship with someone you know, make sure you are on the same page with the type of editing you want and the amount of criticism you can handle.
2) Figure out exactly what you are looking for and tell the beta reader up front. Some authors are looking for a quick readthrough just to make sure the major plot points fall into line and the text has consistency. If this is you, and your beta spends a week tightening your grammar and changing your specific words, you're both going to leave the table frustrated and angry. You wasted her time, and she didn't even give you the big picture, which was all you were looking for in the first place. If you want a partner who sees just the trees, sentence by sentence, say so. If you want a partner who sees just the forest, the piece as a whole, tell them. I've found the best editor is one who does both, but you've got to be willing to part with your genius phrasing and even some of your overarching themes and ideas if you choose that type.
3) Consider some kind of payment plan. I edit for money through a company. I edit for friends for free because, you know, friendship. I edit for my crit partner (who is now a friend) in an exchange program. She sends me her stuff, I send her mine. If the playing field is equal, you'll not have to worry about any feelings getting in the way of your stellar work.
4) There are two types of editors you can choose.
a) Choose a writer who writes like you do. These are good because you know you have a kindred spirit. This person will understand your turns of phrase. They enjoy your genre. They have a general knack for saying things in the way that you say them. Using them will preserve the purity of your work, in that they already 'get' you, so you won't have to waste time changing something for an outsider's opinion...someone who may or may not know what the readers of your work as a general audience will think.
b) Choose a writer whose style you admire. This is the tougher and, in my opinion, the better option. If you have an editor who writes as you aspire to write, they will make the sort of changes you wished you had thought of. They will improve your writing in the way you want it improved (whether you know it or not.) Your words might not stay the same, and you might have sweeping changes to make, and you might have to ignore some of it because the person just doesn't 'get' it, but overall, you'll get a thorough edit on things you otherwise wouldn't have seen.
5) Don't assume people know things. You would think it would be a common courtesy for an editor not to say something like, "wow, this character totally sucks, and I hate him." It's not. If you don't want that kind of language, or that negativity, tell your partner upfront. It probably wouldn't have been an issue, but in case it would have been, now you've covered it and no one gets hurt.
If you don't know where to find an editor, and you're looking for someone who does not know you personally, put out a signal. Join writing forums and groups. You can use Facebook, Tumblr, or even plain old google. Type in your genre and the word discussion. Goodreads is also great for this. Network among writers and readers and you'll find yourself a partnership before you know it.
Good luck and happy editing!