I would first cleanse the stones you have a few opitions. You can look around the site for ideas. Depending on the stones you can use holy water, full moon cleansing, sea salt and the ocean. There are other methods as well.
After cleansing them you can take a stone at a time and meditate with them feel the vibrations and the motions you get from it. Record and then study about the stone. All you need to do is google the stone's name and learn about it. If you do not know the stone is. You can always describe the stones and often times members in the site or google can help pin point what it is.
You are able to reuse these for your own personal practice.
If you feel there are any negative energies surrounding it, or you just want to make sure to boost up the energy of the stones, you can cleanse them.
You can use them in meditation to stimulate, boost, and open your chakras. One way is by laying down and placing the stones in the matching places to the corresponding chakras. Or you can sit in a leg-crossed position and put three crystals in both hands and one in front of you.
These can also be used to simply keep close to you to boost anything like, peace, harmony, happiness, prosperity, etc.
They can be used in rituals, and you can even incorporate them with other magick tools, and they can be used in divination.
There are other ways you can use these, but this is all up to you as this is your magickal journey.
I hope you consider a few things me and a few others have said. Blessed Be!