For me, as a single mother of 2 boys and super busy (as so many of us are). I have found this to be most efficient way to cleanse my crystals each month.
On the full moon of each month (not the new moon) prepare a plate or tray (any material) and place rock salt over the surface of the plate or tray, to cover the entire base
I then place all my crystals, jewellery, tarot cards and any other talismans I use on top of the rock salt.
On a clear night I place the items on the tray and put them outside under the light of the moon to cleanse and absorb the moons energy.
If its raining or outside is not an option for you, find a window where the moon is visible and place the crystals on the window ledge.... this will also suffice.
When you awake, collect the rock salt and find a place to bury it in the ground. Give back the rest of the energy (absorbed in the salt) to mother nature.
Feel free to message me on facebook for any more advice.