Although crystal healing will work, to some extent, in any environment, I have found that the best results occur when you create a sacred space for your healing. I came into the world of healing through Space Clearing and have developed my sensitivity to the energy of a space.
In a room with a clear, high vibration I've observed that clients feel safe, quickly relax and readily let go of the heavy, dense energies that block them, whereas in an energetically polluted space people will subconsciously protect themselves and so resist the healing and hold onto their blockages.
One of the quickest ways to clean up the energy in a room is by using sound. I love using a singing bowl, but I'll also use bells, drums or rattles. Whichever instrument you choose the principle is the same. Sound waves vibrate dense, sticky energy so that it dissipates. I find the singing bowl best for a general clear up as the sound waves move in a circular fashion throughout the space, but for getting right into corners a rattle is often more practical.
I will often air my therapy room by opening a window, if that is impractical then I might spray an appropriate gem essence to bring a fresh high vibration into the space. Before a client arrives I light a candle to invite the Light of the Divine into my healing.