Editing. That is what I have been doing for the past couple of months. A necessary evil, but ultimately worth the trouble.
And for this one I really needed it. I didn't have too many issues with grammar or tense. A few issues with word choice: but & and & well. (I blame my love of Doctor Who for that.)
My two main problems: character that disappear in the middle of the book and a character that I originally had alive but then killed off.
The first one is not difficult to deal with. Go in and find where you left off with them, and see if they fit in any other place. If not, give them a rousing exit. The second one though, wow. I obviously missed chunks of this character. The reason I had the character alive to begin with was to show a couple of things. I write urban fantasy, so with the characters I am dealing with run the gamut from demon to elf to Elementals. Long story short: I had two Elementals kidnapped by demons, leaving behind their two year old daughter that saw everything. Now, some 300 years after the fact, the daughter is looking for her parents. When I first wrote about the parents, this is 300 yrs later, I had both of them still alive. Then I thought that was too clean, too easy, so I decided that I should kill the mother. Not a problem. Until you miss scenes in the rewriting process, keeping her alive.
This is where a REALLY good reader/editor/person that won't hold back come in handy. I sent my novel to a friend to read. She is brilliant, and caught what I did wrong and offered suggestions. She knows these characters, because she has read everything I have written about them. She pointed out the glaring mistake, and then said that she liked the character I killed off.
Hmmm. What to do? After months of thinking, I figured it out. I will keep her alive, but have her separated from her husband. Thereby leading to more angst and motivation for various characters. Problem solved, more avenues to pursue, more headaches...
Editing, though a pain in the butt, can be very rewarding. And having someone you trust give you feedback is very important. The point, no matter what you write, be it UF, SciFi, mystery, non fiction, find someone that knows how you write and what you write. That alone makes a world of difference along the editing path.