I had the colored hair along with the tattoo, and I loved it. I naturally stopped dying green and purple (among other colors) when I decided I wanted a job. It is difficult to find a job with green hair. My father actually was somewhat against me getting a job, mostly because he thought my grades would fail. I was always an honor student so that would have been bad. So the first semester I worked and went to school I got straight A's just to prove to him that I could do anything I set my mind to. I had never gotten straight A's before as there was usually one B (sometimes two) on there, but I still was on the honor roll.
Oh, and you can't very well tell a child that they can't get a tattoo until they are 19 or later because it is legal if they are 18. If they still live at home I guess you could threaten to kick them out, but most of the people I knew moved away from home as soon as they hit the 18th birthday so there isn't really anything you can do about it. And sometimes if you stifle them too much at a young age they will go completely crazy as soon as they are out of your sight. Moderation is the key! But that is just my humble opinion.