Would it be better to get a tattoo to cover up cutting scars or just leave the scars?

It depends on if you cut across the forearm or cut vertically. Cutting down is the right way to do it. I hate it when people cut across the arm because then that makes me think they are silly wannabes who have no idea what they are doing or just doing it for attention. So if you cut horizontally, then cover that up with a tattoo. If you did it the right way, then you were obviously very angry at something or someone and you can let people know that or not. It's up to you. Don't get me wrong. I don't encourage cutting especially if you are a teenager because teenager's brains are not fully functional and so they don't fully understand the consequences. But since you have already...that is my advice.