In the book CA$HVERTISING, author Drew Whitman provides a four part prescription for simpler writing. Even though he is writing to marketing people primarily, his advice can be applied by any author. Pick up his book for more tips on writing and on selling your own book.
ONE: Use Short, Simple Words. Use as many one syllable words as you can. Don't use "big college words" when simple words suffice.
TWO: The Shorter Your Sentences, The Better. You want to have a variety of sentence length throughout your work, but this rule is generally true. Dr. Flesch suggests that you should aim for an average of 11 word sentences.
THREE: The Short, Short Paragraph Trick. Build your reader's momentum by incorporating short paragraphs that they can read quickly. Some author's overuse this technique and their writing appears childish, but it can be applied for great effect as well.
FOUR: Pile on the Personal Pronoun Personality. Talk about real people frequently in your work. "You" is one of the most powerful words in your arsenal, make sure to use it.
Again, CA$HVERTISING has many more great tips on the psychology of writing and selling. It is full of great information, and a great buy for anyone interested in writing and selling.