how do you photoshop a person into a mirror/glass?

i want to photoshop a body into a mirror so then its like they're invisible or some sort of mirror effect on their body i already searched everywhere for this tutorial but i think i know what i have to do but i'm not sure about it! :P

i was going to try just making the person look invisible and keep on blending till they look invisible then put the effect of being a human mirror such like adding glass effect to a shield and sword and the hair too!
but i'm not sure that will would because if i keep playing with the blending mode it might come out all messy >_<

Isn't this just making the layer over the mirror just transparent to 20 percent or something like that. It should show up as if the person is ghosted in the mirror.

There is a few ways to do it. Probably the most accurate way would be to use the lasso tool and painstakingly outline her whole figure. The other way to do it, is use the magic pen tool, but i have no idea how well that would work.