Rule number one: you teach yourself to write. No one else can teach you. Writing is as personal as eye colour. Your style of writing is as individual as your fingerprint. And you learn to write by writing. You discover your style by developing your style. By writing. No one can teach you that stuff.
There are rules about grammar, some of which I’m yet to master – I use far too many commas, and the more I think about trying to reduce them the more I use them – and there are preferences and guidelines too, Hemingway’s disdain for adverbs for example, which I mostly agree with, though there are plenty of quality novels with plenty of quality adverbs, so it’s not a rule. Though it was for Ernest.
Actually, on reflection, there is only one rule for writing. It’s this: you sit down at a table with a pen and a sheet of paper.
And you write.