I really like the concept of mixing your necklaces both short and long to create a dramatic look.  I think it looks really cute with just a basic T-shirt and jeans.  It can also add drama to a dressed up look as well.  Play with the size and shapes of your necklaces.  Really chunky necklaces add lots of texture and stand out, but if you don’t want all that attention you can go for more of an understated look with delicate necklaces.  Have fun and get creative!