Crystals radiate amazing healing energy, each one having a unique vibration to share with each of us. I agree that it's best to go to local metaphysical shop, and maybe one where they are educated about stones and can show you around. Pay attention and you'll feel which one is drawn to you.
It's important to cleanse crystals at times. Some suggest just after purchasing. You can charge them by placing them in the sun, or with some, running under water.(research beforehand because some minerals don't like water) You can also charge them under the moon or with intention. Simply send light into the crystal (in your right hand) and intend whatever it is you'd like the stone to help you with/shed light upon/heal.
Life with crystals is always enlightening. If you listen they will speak and heal. The laying on of stones is considered an ancient art, and its beautiful. I'm sure there are many crystals that resonate with certain zodiac signs. Fire opal definitely having that firey energy, and smokey quartz kinda reminds me of the 8th house/Scorpio/Pluto.
Some of my favorite stones.. Selenite, Amethyst, Celestite, Citrine, Obsidian, Hematite.
Crystals in their raw form are often more attractive to me, but tumbled stones are good for carrying in your pocket. Things to look into: Crystal grids and Sacred Geometry. Here is the atomic pattern of a Beryl Crystal.
