Style: The Basics of Clarity and Grace is an excellent book. I picked it up ages ago, and rather liked it.
A lot of writing advice out there is... weird. There seem to be a couple different varieties. One is "first year university students do X too much, so nobody should do X at all!" This advice is usually "directionally correct" for many writers, but it shouldn't be taken as an absolute. The book Style offers better balanced versions of much of this advice. For example, it shows several examples of when the passive voice can actually increase clarity.
The other bit of weirdness in English-language writing advice goes back several centuries. There was supposedly an "arms race" of grammar advice, where each writer tried to ban more things than the next. The result of this was a bunch of rules that nobody has ever actually followed. Strunk and White is notoriously guilty of this. E.B. White was an excellent writer, but he routinely ignored the rules he proposed. Sometimes he ignored the rules on the very page where he proposed them! This kind of constantly-ignored advice is suspicious, because writing advice should ultimately be based on the common practices of well-respected writers, not on "zombie rules" that have been passed down for centuries without ever having been obeyed.
One good source for telling the "zombie rules" from the useful ones is Merriam-Webster's Dictionary of English Usage. This categorizes advice into rules that good writers actually obey consistently, rules which affect how formal your writing feels, and rules which have no basis in actual practice.
Weirdly, this tendency towards "zombie rules" may be less of an issue in other languages. For all that English-speakers love to make fun of the Académie Française, the Académie's grammar advice seems to be a lot more evidence-based, or at least focused on the well-established differences between spoken and written French.
