Here are some tips to help you get that manuscript as ready for readers as you possibly can -- keeping in mind that if you take out the glaring problems now, your readers will have an easier time spotting the more complex problems.
1. Go through and do a search for "was." Most of the time, when the word "was" is used, you can change it to more of an active voice. Instead of saying, "She was sitting on the porch," say "She sat on the porch." This brings your reader into closer contact with the story, and it eliminates the repetitive use of "was."
2. Go through and do a search for "that." Most of the time, "that" is used when it's not needed. "She thought that he'd be there to pick her up at three." Take it out and see what you've got ... "She thought he'd be there to pick her up at three." It's the same thing, but "that" gets repetitive and makes your sentences wordy.
3. Go through and make sure all your punctuation is still there. I've noticed when I edit for people that as they take out words they've been told to take out, sometimes the punctuation gets taken along with it, erased accidentally by the cursor being in the wrong place.
4. Go through and take out fully 3/4 of your adverbs. Keep only the ones that are absolutely needed -- most are indicated by the context, anyway, and aren't necessary.
There you have it -- four steps to help make your manuscript ready for readers. These aren't the only things to watch out for -- there are many -- but these are the most common mistakes and the most common detractors from the story. With these things out of the way, your readers will be able to concentrate on the things that remain and help you polish the story until it shines.