100 Ways to Improve Your Writing by Gary Provost is from 1985 and has aged remarkably well. It's a set of rules, short and to the point. Some advice is dated and not relevant any longer – a couple of hints on how to acquire information and in which format to submit your work, mostly. Apart from that, the book talks about how to prepare for writing, how to structure texts, and goes down to details of grammar and punctuation. All of these things are well-structured, to the point, and come with plenty of examples and as much entertaining writing as you can fit in a paragraph or two per topic. I enjoyed the short form and the sensible advice – some of which is very common, but especially the sections on editing contained new advice for me.