Ever wondered how to clean that chandelier in your house without breaking it? It's quite easy really (unless you have a really large one, in which case, you should get professionals in)
Get a plastic bag large enough to cover each of the fittings (make sure the bulbs are cool before doing this). Tie one end over the light and let the bag sit behind the fittings like a backdrop
Put some newspaper on the ground to catch the dirt and water.
Dust gently with an acrylic brush (a paint brush works well).
Put some cleaning solution in a plastic spray bottle and spray close to the fitting to dislodge the dirt.
Allow to dry.