My writing guideline is its purpose, influenced by The Adweek Copywriting Handbook, some of the axioms list here:
Axiom 2: All the elements in an advertisement are primarily designed to do one thing and one thing only: get you to read the first sentence of the copy.
Axiom 3: The sole purpose of the first sentence in an advertisement is to get you to read the second sentence.
Axiom 6: Your readers should be so compelled to read your copy that they cannot stop reading until they read all of it as if sliding down a slippery slide.
My job is not exactly the same as a copywriting, but still need to stick to these three axioms above, which are the key to a professional writer, other important guidelines are using rhetoric and follow the style, not necessary but still about the quality
Use thesaurus is important to an English writer, write Chinese is the same, so I use this website to find Chinese synonyms
At last, I will read as more book review I can on Goodreads and Douban, to draw the inspiration, rich the content and improve the quality, hopefully, a perfect delivery