To give the package the illusion of bulk and shine we'll add some highlights around the edges of it.
While they are comprised of more of an organic shape it's still important to have a general idea of how reflections work.
Below you'll notice that toward the edge of the package the lines are smoother. Towards the center of the package the lines taper down to a point. This suggests that the plastic has something inside it causing the plastic to protrude where the object inside meets the plastic. So, as the highlight reaches the center it is likely to come to a point. Again, there is no finite method but this technique seems to be realistic enough.