I purchased it 1 size bigger as everyone suggested since it's a girl's shirt.  I usually wear small or medium so I bought large. And I bought two of them because I too, was going to wear the shirt as my work shirt. (I'm a waitress also.)

I opened it and was shocked.  It looked HUGE.  I feel like Medium would be the right size for me (then the shirt would fit me like the model in the picture)because I look like I'm wearing my boyfriend's shirt or something.

So I would suggest getting one shirt at a time.

Other than that, it's made very sturdy, and black is staying black after many washes. I love the button down collar.