Rules.

Notation rules and conventions are a funny thing. If there was just one way to present the material, we would not have a new notation guide produced every decade or so. Notation, though it has set conventions and rules to follow, is constantly evolving. I have been making my way through Elaine Gould's tour de force Behind Bars. It's a spectacular new guide for today's engraving practices, and a must-have on your reference shelf, but certainly not the final word on notation. When engraving is approached as art, rules can become a burden. A good engraver will adhere to as many conventions as practical. However, music is not all created equally. Learn the rules, and learn when it's acceptable—even preferred—to break them in a thoughtful and meaningful way. Consider yourself like a writer, maybe even a poet—form the symbols in the most meaningful and beautiful way you can. Never let your notation get in the way of the performance. Definitely never let a rule in a book obscure the music. If there is a clearer way to notate, think about it, and artfully incorporate your experience and context into your work.