This from Dr. Robert Bolan of the LAGLC. 

I agree with Rob’s choices of writing references. Strunk & White and Zinnser are indispensable and, perhaps not so surprisingly, they are written well enough so they actually can be read and not only used as quick lookup sources. Of course there are others but these are touchstones of proper English grammar and word usage.

So much of good writing, as Rob suggests, is trying to achieve absolute clarity with the words you choose and how you string them together. Economy is a sacred principle in good writing. Use the right words and use as few as possible. Also, rearrange sentences to get the flow right. For guidance on these skills I like Getting the Words Right: How to Revise, Edit & Rewrite by Theodore A. Rees Cheney. For assistance in technical writing there are several references. I like Merriam-Webster’s Manual for Writers & Editors. For sheer brilliance and clarity of advice, check out Robertson Davies’ Reading and Writing, a slim volume you can read in two or three sessions (read slowly, let sink in, do not gulp this one down). And finally, I offer my fervent belief that scientific writing, although requiring parsimony and precision, need not be dry and devoid of style. Read anything by John Gardner on writing, Stephen King on writing, Eudora Welty on writing, or any novelist or essayist whose style you admire. And then when you’re done with all that, read Paradise Lost—aloud—not for comprehension but for the sheer thunderous music of it. Philip Pullman, who wrote the introduction to my edition of Milton’s masterpiece, remarked that "the experience of reading poetry aloud when you don’t fully understand it is a curious and complicated one. It’s like suddenly discovering you can play the organ." You will likely be thinking that poetry has nothing to do with scientific writing. I disagree. All writing exists for the purpose of communication. Again, scientific writing need not be sterile—although that often appears to be the gold standard for editors. If you have something important to say, you must say it clearly, of course. But cadence and musicality, sparingly used, can deliver your meaning with an elegance that will, unbeknownst to the reader, nestle it into place with crystal clarity. Compose, don’t just write.

Obsessive attention to nuance and detail in writing can be a curse as well as a virtue, and every true writer can identify with the following. A friend of Oscar Wilde’s is reported to have asked him what he did yesterday.  Wilde replied: "In the morning I took out a comma. In the afternoon I put it back in again."

Me again regarding this last: A wonderful short essay on being too critical of yourself early in the writing process is Gail Godwin's The Watcher at the Gate.