I agree with what 312robin said. In my younger days, I would spend hours trying to hang art up on the walls, only to finish and realize that everything had gone haywire along the way and I'd have to redo it. Then, when I'd take the pictures down to redecorate I would have fifty holes in the wall where I had rehung the pictures to be straight in the first place! LOL!
Anyway, after I called Ilevel, I never went back to the DIY-self of yore. I call them for any job I have where I need everything installed quickly, professionally, and safely. If you call, make sure you ask for Patrick, he's the best at what he does and not that hard on the eye to boot!
Pros: professional and safe artwork and mirror installation
Cons: everyone isn't like them