Providing backlighting only to a figure can indeed make a silhouette, but you will get some highlights on the curves of the body etc, and of course any hair or clothes. You might want that, for the moulding and shaping it performs.

However, if you want the hard almost 2D effect, then you will have to provide a background, strongly light that, and leave the figure dark.

Experiment with relative distance of the background to the figure, and where you place the lights. Spolights will be best as they throw the light only one way.

So, from back to front:

A background, some lights for the background only, the figure, and then the camera.

As for the "real world way" to do a silhouette, well the above is it. The idea of having a sheet between the camera and the figure is not silhouette, it is shadow.

Trust me, in the "real world" I am a lighting designer... ;)