Wow. Can anyone tell me what the heck is going on with this thread? Has everyone who's posted in it so far (besides Spanner and myself) been banned? Am I placing a curse on myself by joining this list?
Geesh.
Ok, now... Maggie: "fifty chapters" doesn't really tell us anything. A word count would be more helpful. Truth is, though, that you aren't likely to find someone who has that kind of time.
The best advice I can give is to go and visit the Share Your Work board. Don't post anything, just read through what others in your genre have posted. You're likely to see them making the same sort of errors that you make, and see how AWer's suggest that they be corrected.
You may even consider doing crits. Anything, even, "I liked it" is helpful to the original poster, because it gives feedback, and to you, because you can analyze what you liked/didn't like and think of how what you said applies your own work.
If your problems are really basic, and you have a lot of grammar and spelling issues, then run things through a word processor's grammar and spelling checks and then read through again, trying to catch whatever new mistakes the word processor created. If you aren't at a level where you can do that, get there. It's essential if you really want to be a writer.
Once you've done those things, post a small snippet, preferably one that you feel is typical to the overall work, and see what the good folks on the Share Your Work board think of it. They'll probably point quite a few issues, and some of those issues will probably be repeated throughout the manuscript. Having them pointed out to you will allow you to fix your own work.
Don't take this to mean that I don't have faith in your writing ability. Anything ever written can be critiqued, and almost everything ever written has flaws. The purpose of SYW is to find those flaws so that you, as an author, can decide which really need fixing and which are a part of the feel, flow, or voice of the writing. Writing (especially grammar) can be made to look very set-in-stone and clinical, but in the end, it's more art than anything. But as with most other arts, you have to know the rules before you can break them.
Anyway, I'm just rambling at this point...sorry...hope there was something helpful in there!