Some Book Recommendations
How To - Start a Home-Based Writing Business - Lucy V. Parker
Getting Started as a Freelance Writer - Roberts W. Bly
Starting Your Career as a Freelance Writer - Moira Anderson Allen
Make a Real Living as a Freelance Writer - Jenna Glatzer
A Writer's Resource. A Handbook for Writing and Reserach - Elaine P. Maimon and Janice H. Peritz
The Elements of Grammar - Margaret Shertzer (there are tons of grammar books out there but I love this as it is really simple and no nonsense)
A Pocket Style Manual - Dian Hacker
The Copyeditor's Handbook - Amy Einsohn (every editor who I've ever spoken to has told me you will be put one step above the rest if the piece you follow the rules of basic copyediting and grammar)
Writer's Market, and Writer's Market Companion - Writer's Digest Books (also online versions)
The Write-Brain Workbook. 366 Exercises to Liberate Your Writing - Bonnie Neubauer (a great book for getting your writing muscle working - challenge your friends and family)