I've been into crystals for a while now, and I've found them to be real and powerful.
There are three ways to find crystals.
1. You can go to a gem mine and mine your own.
This is the best way, because you brought the stone out of the body of Mother Earth (this isn't a bad thing, and it doesn't hurt anything at all) and the first to touch it is you.
2. You can go buy them from a rock shop, gem store, and jewelry store.
This is ease, but the only drawback is that the crystals have been handled by tons of people. You can easily 'cleanse' the crystal physically and spiritually.
3. You can find them being washed up on shore from a lake, steam or the ocean. This is a good way to find a crystal, but you are never guaranteed to find any. The Ocean is the very heart of Mother Earth, and finding a crystal directly from the ocean is by far the greatest gift the planet can give you (aside from life).
Finding crystals from the earth (from a field, or source of water) is good, and doesn't always require cleansing, but if you feel any negative energies from the crystal, cleanse it!
If you get some crystals from the store, always cleanse it. Even if there is negative energy that was not willingly placed into the crystal, there could still be some there. Better safe then sorry.
The best crystal to start off with is Quartz.
But if you feel strongly connected to another crystal, that is the crystal calling to you. You should get it.
(I've been pulled to an Amethyst crystal, but the cluster itself was more expensive then what I had with me, so I wasn't able to buy it. DO NOT STEAL CRYSTALS)
Clear Quartz is very nice, pretty and fairly cheap (prices will change depending on where you are).
It is charged by leaving it in bright sunlight, even better if left by plants.
Clear Quartz is good for amplifying your inner physic abilities (don't expect to be reading the future and everything, just keep working on it), it can clear chakras, help channel Spirit Guides and Angels.