Zinsser's "On Writing Well" is the midpoint between Lamotts "Bird by Bird" and Wood's "How Fiction Works": more personal than Wood and more craft-centerd than Lamott. The primary difference between his "personal" and Lamott's is that Zinsser tends to stick to stories from his life that center around writing: being a guest speaker, interacting with his students, being a featured pannelist, whereas Lamott tends to center her experiences and rotate the writing tips around that (not unlike Chee in "How to Write an Autobiographical Novel). Zinsser is explicit about what he thinks is good writing versus "hack" writing, being as bold as to say "hack" himself.
Zinsser is hyper-aware of the prominence of non-fiction writing and offers valuable information for writers and non-writers alike. His book is broken into four parts: principles, methods, forms, and attitudes. However, for most people (i.e., anyone not pursuing journalism) the principles and methods sections are where a bulk of the information come from. A lot of the actual "tips" stop after this point, where he begins to get specific about forms and clichés to be mindful of once the book hits the "forms" section. At that point, you can really skim to any area you're interested in and leave the rest untouched.
Zinsser has a few recurring tips: be yourself, avoid clichés, all elements must be cohesive (unity), and, perhaps most important, writing won't be any fun to read if you don't have fun writing it (enjoyment). That being said, Zinsser's first couple sections open the door for anyone to learn how to better their writing abilities and become aware of what their pitfalls may be.
