Here's MY rules:
1) There Are No Rules.
2) If in doubt, check #1.
Oh, sure, there are rules governing grammar (and if you use it's instead of its when you know better I will COME AND FIND YOU...) and there are certain guidelines which govern storytelling inasmuch as following them makes for having a coherent tale (in fairy tales you start with "Once upon a time" and not with "And they lived happily ever after". Know your scene-and-consequence, is all I'm saying).
But ANY rule/guideline/suggestion/demand is there to be mocked and broken... if you know how to do it. Which means that the only "Rule" is really writing the best story you know how.
Learning how do to this requires plenty of practice and plenty of heartbreak. That's the way the cookie crumbles; if you're in the game know these things in advance and suck it up. For the former, you bear the only responsibility - nobody can practice your craft for you, do the work or don't complain when you have to face the consequences thereof. For the latter, well, that's what your support systems are for - your friends, and your fellow writers, people to whom you can whimper a little before you gird your loins for the next battle.
But don't "write by the rules". Write the story that rules YOU.