Once you know what a rule is and why it exists and how to follow it, then break it, and then ask yourself how that feels.
This is a fairly foundational prescription for any budding writer: learn your Strunk & White, then see under what circumstances any given rule can be bent or broken, and to what end. I like how Zach throws in "then ask yourself how that feels" at the end of it, because not all of us are going to indulge in the same things we like as a writer that we might as a reader.
The main thing, though, is that the whole point of bending the rules is not necessarily to impress others, but to push yourself, to get yourself out of your own self-designated comfort zone. Don't think this is limited to anything strictly technical — e.g., writing in first person when you've preferred third, or the other way 'round. It also means not settling for the same subject matter or the same set of POVs that inform your work.
You can make a career as a writer repeating yourself. Find something that people like to curl up with, and you can dole it out to them in various permutations and combinations. But the danger there is in doing just that — in giving people what they want, in oh-so-slightly different forms, over and over.
The danger isn't even in being an entertainer; it's in becoming an entertainment machine.