As a manuscript assessor, I know a lot of first time (and tenth time) writers make mistakes. Some of these are basic mistakes that are obvious, once pointed out. Unfortunately, they're obvious only to someone who already knows the score.
Since the same problems pop up over and over in manuscripts from widely differing authors, I coralled some of them in writing guides which I self-published through http://www.lulu.com/ .
Self-publishing let me get the guides out right away. It gives me the right to sell tem directly, and also to revise them whenever I choose. They are available as PDFs or as paperback books. Titles include "Writing a Picturebook Text" (what to do and, even more importantly, what NOT to do), "20 Top Tips - the Unwritten Rules of Writing", which is a distilation of all those errors I've met, and made, in nearly 40 years of writing, "Writing Metrical Verse", "Creating a Fantasy Setting", "Writing a Manuscript Proposal" - and five guides that cover Ideas, Plots, Characters, Style and Dialogue.
These guides are available from the Affordable Manuscript Assessment site at http://www.affordablemanuscriptassessments.com/workshops.html or directly from http://www.lulu.com/sallyodgers .