After trying a specially-made attachment on the vacuum cleaner to get grime off painted metal mini-blinds, we resorted to a liquid cleaner and a dry cloth. The vacuum cleaner did a fair job of dusting the blinds, but a film of dirt remained.
Ordinary glass cleaning spray can be used on blinds, but each slat must be wiped individually. For something easier, buy spray-on chandelier cleaner at a hardware store or a store that sells lighting fixtures. After the chandelier cleaner is sprayed on, dirt forms beads that are simple to wipe off using a clean dry cloth.
Make a substitute for chandelier cleaner by putting 3 parts purified water and 1 part isopropyl alcohol in a spray bottle. This concoction might harm the finish of plastic blinds, so anyone wanting to use it on plastic blinds should test it on a small area first.