Wearing leggings is the easy part when it comes to bottoms. The hard part is what top to wear that goes with the leggings. Black leggings is easy to pair it with a white long cardigan top. If it is summer, you can always should a somewhat long white t-shirt. If you want to give a more formal look, you can pair it with a white silk blouse. When you wear black leggings, you can practically wear any colour top. However, it depends if your complexion and hair colour in order to give an overall look.