Always start in the middle of action! Never start with dialogue! Give us some emotional context before you jump into the action! Always start with dialogue! Never use dialogue tags! Only use dialogue tags like "said" or "asked." Make sure your protagonist is likeable! Don't make your protagonist a boring Mary Sue!
The list is endless.
Regarding any "rules" of art, I have a few thoughts.
One, that anyone who tells you that there is only one way to create a work of art is a) gravely misinformed or b) hopelessly reductive and/or c) probably trying to sell you something, mostly likely his overpriced class/book/seminar.
Two, that if there *were* one clear set of rules of fiction, writing books would be way easier and also way more boring.
Three, even within the context of certain "rules" that you have decided make sense and apply to your own work, part of the fun of creation is exploring ways to subvert, bend, push against, or upend them.
Four, with writing (as with all good and creative work), anything that helps you to keep going, keep writing, and keep creating is good as long as it works for you. Anything that keeps you from writing and stops you from creating is not currently helpful, and should be (at least temporarily) ignored. Ultimately, writing is about figuring out how your own mind works, how your own creative brain works, and what works or makes sense to someone else might not work or make sense to you, and that's PERFECTLY FINE.
If all of that is too much to process, I have made a flowchart to help you decide whether or not you need to worry about all the "rules" of fiction floating around in your brain, and how they should or should not apply to your work-in-progress.
That should clear things up. :-)