I'll be honest, I struggle with editing - A LOT!!!
I have to make myself NOT edit or I'll never get the first draft down. But then I have to remember to switch gears into editing mode after I've got it written. And then, again, I have to switch off editing mode when I'm reading someone else's book or I can't fully enjoy their novel. But then I have to turn it back on again when someone asks me for a critique. And it goes on and on. I am doing much better with the on/off editing switch, but it does get confusing!
So here are a few tips I've learned about editing that have really helped me (You've probably heard them over and over again, but they work! That's why we all keep using them!)
1- Let your draft sit! You have to give yourself time without your manuscript or you can't read it with fresh eyes. This is a killer for me cause I want to jump in and get it done, but if I do I'm going to miss a lot of important corrections.
2- Know your crutch words .... and then avoid them! I have crutch words. The words I use ALL THE TIME! But I never seem to see them when I am reading the manuscript. Some of my words are look, gasp, jumped, blush, and there are others but I can't think of them right now (see, you don't always know your own crutch words!) Use a word counter tool, such as wordle.net or other word counting tools that will show you the most used words in your manuscript. Then use a thesaurus to find new words to get across the meaning you want. Some of my favorite thesauruses are here: http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Dstripbooks&field-keywords=thesaurus%20by%20ackerman
3- Read aloud! Seriously, I felt ridiculous the first time I started reading aloud to myself at home. There was nobody around and I had avoided reading aloud because I thought it would sound silly. Well it does sound silly, and at first I was extremely self conscious about reading aloud to myself. But then I began to hear the sentences and finding little mistakes that I had never noticed, no matter how many times I read it in my head. And I found ways to restructure sentences to make them smoother, more polished, and flow better on the page. It was such an amazing discovery!
4- Don't be afraid to let others read your work! Other people are going to see your work different than you. You have this whole world created in your head that you see every time you look at your story. Others don't have that world, so they see only what you have shown to them through your writing. They are going to let you know if things don't make sense, or if you've forgotten to give the reader details from your world that are important.
5- Get a professional editor! Once you have done everything you can for the editing of your book, then get a professional to do it. You don't have to break the bank, and if you have an agent or a publisher already they will probably help with this step. But if not, look around, ask around, find out what editors your author friends have used, and go to them to make your piece shine. Querying with a manuscript that has not been professionally edited could be a risky move, so rather than worry over issues that may or may not be there in your writing, just take the time and spend the money to make it clean. Then you know you've done everything you can and it's out of your hands once you send it out.
Those are my tips - the things that have helped me. Take them or leave them as you like!