Poets & Writers has a series of online craft essays. They take just moments to read and are usually useful. Here is a representative example.
Brain Pickings has collected the advice on writing that they’ve shared over the years. This advice always has excellent authors as its sources.
Finally, Literary Hub lists short excerpts from 25 books on writing by famous authors. If nothing else, the list acts as a possible shopping list for books on the craft of writing. The excerpts can help in deciding from among all the books.