Simply moisten a soft cloth with lukewarm water and wipe both sides of every leaf. As you work, support each leaf with your free hand. You can also wash leaves by misting with a pump sprayer or you can set them in the shower under a fine spray. As you clean, check for pests, which can sometimes be removed with a healthy spritz of water. Cacti, with their sharp spikes, are a bit trickier to maintain.
Many cacti also have a waxy coating that helps the plant conserve moisture in desert climates.
If water gets on that coating, it can act as a magnifier, and that magnifier can sun-scorch the leaf. To protect this natural waxy defense, use long tweezers and carefully pick off any stray particles of dust or dirt. Fuzzy-leaved succulents are also sensitive to being touched. The fuzziness protects the plant in arid conditions and washing can be hazardous to the leaves. Instead, use a soft paintbrush and very gently dust off each leaf.