Tribes pierced the lips of women before marriage, and stretched the piercing to mark the times. They pierced the cheeks of tribe members, and wore bars connecting the piercings.
Nose piercings began 4,000 years ago in Middle East as they were thought to make childbirth easier due to the placement of the female reproductive organs. Rebekah, in Genesis was, even, given the gift of a nose ring. In many cases, in history, facial piercings were the mark of higher rank in society.
Today, we still see these piercings amongst our culture, as well as many other facial piercings. Facial piercings, as well as other body piercings serve as a mere aesthetic purpose.
Piercers of today, do not fall for historic guidelines, but instead, the thinking is rather "if it protrudes, it can be pierced." If you are thinking about getting some facial piercing, you need to think about healing, as it takes greater care in healing a facial piercing, as for the most part, the face is a flat surface. Plus, the face has several vital areas to which blood travels, so you want to watch healing and infections, as well as rejection and migration.
Because modern society is not like the tribes who practiced face piercings, you will want to consider many things if you decide to get a facial piercing. Consider your job, as most jobs will not allow facial piercings; consider what happens if it gets infected and you have a scar on your face; and consider every possible disadvantage before you get the piercing.