Some masterclasses on the nuts and bolts of great writing are to be found in great books.
Others masterclasses in writing style are to be found in, well, masterclasses in writing style.
If you write for your job, or for any reason whatsoever, you must read the legendary guide, The Elements of Style by William Strunk, Jnr.
It will make you better. Stephen King swears by it; you should too.
For anyone too macho to read those 13,000 tight, precise, succinct words on the subject, please, try Ernest Hemingway’s writing bible, the 2,300 word Kansas City Star Copy Guide.
Both are invaluable. Only break rules you know exist.