The best thing to wash plant leaves with is plain water and a soft cloth dampened with the plain water.
You can spray some plain water on the plant leaves and then use the damp cloth to help clean the leaves and remove dust and grime.
If the grime is really stubborn on the leaves or you also have pests on the leaves you can use a mild soap and water solution.
You can also use some diluted vinegar or lemon juice to clean the leaves especially when they have hard water spots.
To clean and wash plant leaves you can also use a mixture of neem oil water and Castile soap in a spray butter and then use a damp washcloth to clean the leaves with.
When cleaning or washing the plants leaves you should support the the leaves with one hand while cleaning it with the other.
This makes it easier to clean the plant leaves and avoids bruising or damaging the leaves or plant.
A tablespoon of Murphy's oil soap in a quart of water can also work to clean the leaves when placed in a spray bottle and sprayed on the leaves of the plants.
Then you can simply wipe the plants leaves down with a damp washcloth.