Zinser’s book is a classic. In fact, it is recommended almost as much as Strunk and White’s Elements of Style, and that’s a high compliment. Mine is the 1996 edition, but the thirtieth anniversary edition, published in 2006, is on Google Books, where you can sample portions of the book. Click here.
Zinser advocates simplicity, avoiding clutter, which boils down to this. “Never use more words than you need, and use language that is easily understood by your target readers.” Don’t dress your writing up with jargon or flowery language that does nothing to clarify your point. Zinser goes into detail on specific types of writing, like travel writing, interviews, memoir, scientific writing, and more.
This is a book that you will take out and read at least annually as a refresher course in good writing. The new edition seems to contain much of what’s in the older edition, so if you’re pinching pennies, you might find a used copy on Amazon or Half.com.