A few of the piercings that may be performed with 15-gauge needles include tongues, navels and earlobes. If you plan to stretch your earlobes, which some people incorrectly call "gauging," piercing with a 15-gauge needle allows you to skip the stretch from the usual 18 gauge ear piercing. A piercing performed with a 15-gauge needle generally is no more painful than one performed with an 18-gauge needle. Both make a clean, quick cut through the skin.
The process of stretching the skin should be a slow and conservative one. Stretching too quickly can lead to "blowout," which means that the skin at the back of the piercing pushes out through the hole. This leaves a lip of skin that can become quite pronounced. Stretches are usually performed with tapers, which look like blunt-ended piercing needles that increase in size from the tip to the end. Stretching is faster at first, when the difference between gauges is slight. As the hole grows larger, many stretching fans choose to apply one wrap of Teflon tape to their jewelry every few days.
The process of healing any body piercing is the same. You should soak the piercing twice a day, for 10 minutes at a time, in a saline solution made with warm water and non-iodized sea salt. Depending on the location of the piercing, you may be able to immerse it in a cup of water. Piercers often sell saline spray as an alternative to soaking. Immediately after soaking your piercing, you should wash it with fragrance-free antibacterial soap and dry it with an unused paper towel.
Body piercings should only be performed by a piercer trained in proper technique and prevention of cross-contamination. If possible, find a piercer certified by the Association of Professional Piercers. You should never use a gun to pierce any part of the body, as they cannot be autoclave-sterilized. Experienced piercers will have a portfolio in their shop. Look through the piercer's portfolio to make sure it includes multiple examples of the piercing you want.