Here is a list of books that I have found to be very helpful and insightful for the beginning writer. Not every suggestion is one that every writer will use, but if one can glean one or two points in any of these books that would be useful to them they might benefit tremendously.
Next Word, Better Word: The Craft of Writing Poetry by Stephen Dobyns
Clear and Simple as the Truth (2nd Ed) by Francis-Noel Thomas and Mark Turner
You're Funny! Turn Your Sense Of Humor Into A Lucrative New Career by D.B. Gilles
The Book On Writing: The Ultimate Guide To Writing Well by Paula LaRocque
The Art of War for Writers by James Scott Bell
Plot and Structure by James Scott Bell
Zen in the Art of Writing by Ray Bradbury
Elements of of Writing by James Kinneavy
Roberts Rules of Writing by Robert Masello
Fiction Writer's Workshop by Josip Novakovich
On Writing Well by William Zinsser
These are extremely helpful to the beginning writer, but I believe that the best way in which to learn to write well is by example. To be a great writer, it is necessary to read what great writers have written. For example: Virginia Woolf, William Shakespeare, Jane Austin, and even Plato wrote a line or two that is most extraordinary. By reading what master writers have done with words, we can broaden our own understanding of the use of language and communication. After all, as writers, we are first and foremost communicators attempting to engage the reader in our thoughts and feelings in an attempt to create a connection between the characters and the person reading our words.