If I got a release form signed from an adult that wanted me to tattoo them for no fee. Could I be held liable?

I am a tattoo artist that got apprenticed at a licensened shop in wisconsin and learned all the sterization, and proper tattoo care methods, but chose to go the music route. Now 10 years down the road I picked back up tattooing and I am in Austin and my friend wanted a tattoo. If I get him to sign a release form and dont charge a fee can I get in trouble? I know how to be sterile and safe, so please dont comment idiotic notions of calling me a scratcher.