Leave your crystals out in direct sunlight to be recharged, but be careful. Some crystals, such as quartz, especially crystal balls, may cause a fire risk.
Exactly the same as with sunlight, but with moonlight. Beneath a full moon, leave your crystals out to charge, and this comes with less of a fire risk.
Frankincense and sandalwood are best bets for crystal cleansing with incense. Waft the smoke over the crystals you wish to cleanse, and, as an up, it will leave your room smell gorgeous.
I prefer using white sage to smudge with, but you can use other herbs if you want. As with incense, waft the smoke over the crystals you wish to cleanse, though this is traditionally done with a feather. You can just use your hand or move the bundle around the crystals yourself.
It sounds odd, but you can simply breathe on your crystals to cleanse them. Breathe in deeply and exhale onto the crystal, focusing on cleansing it of negative energy.
This one is a lengthy and dirty process so I tend to not do it, and you shouldn't do it with soluble crystals as they may be destroyed. On a full moon, bury the crystals you wish to cleanse, and UNEARTH them on the next new moon.
AMETHYST, QUARTZ, CARNELIAN
Place the crystal you want to cleanse on a bed of amethyst, quartz cluster, or inside a geode. These two crystals are excellent for cleansing other crystals. Also, placing carnelian in a bag of crystals will mean you'll never have to cleanse those crystals again.
Singing bowls and bells are perfect to cleanse crystals, but any other sounds such as chanting and drumming are just as effective and rid the crystal of bad vibrations.
Practicing reiki on your crystals is another good way to cleanse them.
Holding crystals under running water or in sea water can help wash away negative energies, but, as with the earth method, do not use this method on crystals which are friable and soluble.
This method is a good substitute if you want to cleanse your crystals with sea water or earth but they're too delicate to do so. Just cover them in salt overnight and be sure to brush off all the salt afterwards as it could damage the crystal if left unclean.