grunge tends to be on the simpler side of aesthetics, meaning you don't need to do much to accentuate. the ones you choose can help define your look a little more, and help personalize it. beanies are a popular look, as well as rings and belts.
jewelry: silver rings, long chain necklaces, little stud earrings
bag: solid coloured jansport bags (usually with pins + patches)
belts: thick black with silver buckles, sometimes with chains attached