There are a host of reason. The best thing you can do for yourself if you are considering getting a piercing, is to visit a professional studio. Your decision on where to go and who to have perform your piercing ultimately rests in you hands; do you homework!
When you visit a professional, you are not only getting the knowledge and experience they carry with them, but you get a place to ask questions, and a person to help you solve problems that range from what stone looks best in my navel, to, does my navel look infected?
From a health standpoint, visiting a local studio is a no brainer. A piercer using proper aseptic technique and freshly sterilized tools and jewelry offers an infinitely greater sense of comfort than a friend or home piercer who may be using inferior and ineffective methods of disease control and transmission.
Encountering a problem with a piercing? Trouble shooting from an experienced piercer is a lot more likely to be effective than with advice from a friend. A piercer can assess your particular issue and give advice based on first hand observation of the affected area.
So many reasons to see a piercer. Don’t leave your hands in the body of unskilled hands.