For someone who isn't quite fond of their bare arms (umm, me!) - throw a cape over any top.
For a boho/Olsen/hippie inspired touch to any outfit - add some fringing (bags, vests, shoes).
For that messed up, out of it, on the street effect - wear a ripped up tee, shredded to pieces.
Stone and black pieces will always be a love of mine. I was randomly watching the Trinny & Susannah show on the weekend and they were talking about how most women who wear black wear it because they don't know what colours suit them best, and therefore are scared of colour. I have a basic idea of what colours suit me, but blacks and greys always just seem to suit my mood the best. On the random occasion you'll see me step out of the house in a crazy bright colour if I'm feeling up to it, but most of the time the only colour I wear is on my nails.