The Massachusetts Attorney General has issued updated guidance for boards of nonprofit organization. While the AG is suggesting that this guidance is based on "best practices" the guidance likely holds water enough that the idea there are best practices can be laid aside. And no, in my opinion there are actually no existing formal "best practices", that is evidence-based, tried and true approaches to nonprofit governance. There are common sense practices and better practices but there is little or no literature that provides research-based evidence that there are particularly proven approaches that should be followed in board governance.
That said, there is a lot of common agreement that certain approaches do have a more positive impact and that's pretty much reflected in this Massachusetts AG release. I will note though that the AG highlights there to be only two fiduciary duties: care and loyalty while obedience has 'till at least this moment been recognized as a third duty (obedience to mission that is). Curious but the AG is the lawyer of the land (or at least Massachusetts). Perhaps there is a feeling that enforcing obedience to mission is just not as easily accomplished at the duties of care and loyalty (aka, conflict of interest).
Anyway, check it out. Much of what is outlined is a very good and common sense approach and reference to governing.