I like tattoos in general, I am hesitant though because I am still trying to lose weight and I have kinda a big tattoo planned. I don't want it to get messed up.

If you are using it as a helpful method in a reminder sense like the 'check it before you wreck it' or like putting pretty/inspiring art to make you feel soothed to look at, but I don't see how it could sub for NSSI urges.

But if you mean decorating yourself with inspiring art, why I think that's a great idea I try to make my areas filled with things which I like. Especially my work area.