This is all great advice, but I would add to that biscuits and gravy is terrible if there is no black pepper in it. It's definitely a required ingredient. Sage and others are optional, but pepper is a must.
And don't skimp on the sausage. The number one mistake that restaurants make is skimping on the sausage. It shouldn't taste like milk.
The number two mistake that restaurants make is trying to make it fancy and adding too much random stuff to it. You don't need to add bacon and green onions and cheese and on and on. It's not grits. It's delicious on its own as a nice, simple recipe.