to add to Cpt. Obvious' statement above.
If you dont have any "hard points" to attach the armor to, I would recommend creating a sort of under harness.
Nylon straps and quick buckles are cheap and affordable. I have read a few of the stickies and they tend to not cover the subject super well, fortunately I have experience in armor hanging.
I myself use the Hardpoint method of mounting, but my wife uses a underharness ( that way she can just wear a Underarmor suit and not be all bulked out by Impact gear, dont ask its a girlie thing with her.) I will shoot some pictures when I get back home on friday and PM them to you.