Now that I've covered common technical errors, I'll move on to regular stylistic issues I've seen in my manuscripts and those I critique. It's funny: many of the mistakes I spot are the same as those that are in my own work. :)
1.) Talking Heads belong in the 80's band, not in your story.
"Blah Blah Blah"
Who is talking here?
2.) Lack of emotion. I used to get nailed for this one all the time. It's a fairly easy fix. "Blah Blah Blah." Her hands shook as reached forward.
3.) The White Room, or lack of setting. Christine Moore did a lovely workshop on this at the IWL conference. Until you say otherwise, the reader will picture your characters in a white room. This issue often goes hand in hand with the talking heads. Again, it can be an easy fix. Her hands shook as she reached forward to push a soggy branch out of the way. The pelting rain mixed with her tears.
4.) Scenes where nothing happens Whether it was a struggle to get in the daily word quota or one was was focused on characterization more than plot, I don't think anyone is immune to this. This issue can be fixed either by having the character thinking about the main problem of the story or including some sort of action amidst the ennui. ...and if it's really dull and pointless, you can always cut it.
5.) Anti-climatic endings Often we writers are so excited to reach the ending of our project that we rush through the ending, thus cheating our readers. During the rewrite we all must remember to go back and draw out the ending to the heart-wrenching suspense it deserves.
6.) Someone acts out of character Sometimes this happens because we're still getting to know our characters. If that's the case, then one may cut the scene in which they are not themselves. Other times the author means for the character to grow or change in some way and that is why they act out of character. In that scenario, the author must go back and emphasize the character's growth and changes so the event is more believable.
7.) Repetitive statements/ actions. In one project I was trying to find a way to introduce the back story so I tried it out in various ways and forgot to cut all but one. The result: an overdose of redundancy. Then there was the time when I was trying to point out a character's habit but I overdid it and drove the reader crazy. And one time I read a manuscript where the heroine was falling asleep so often I asked if she had narcolepsy. In return, the author called me on my hero's constant smirking.