Receiving energy with a crystal is as easy as projecting. Again you need to attune and forge a connection with the stone of choice. Once you can feel the energy flowing between your being and the stone and the flow takes on a circular sensation. Then all you need to do is to pick a third energy or being to bring into the equation. Focus on the energy of your choice and feel the vibrations flowing through the crystal and into ones being. The reason there must be a circular flow is that one does not want to overload you or on rare occasions the crystal. In this way the crystal will take on as much energy as it can and so will you. 
As you practice you can employ this technique to charge a stone with a specific energy or to cleanse or recharge yourself.

These are all basic concepts with any kind of energy work there are always thousands of variables and it is our experience perception and the specific goal and energy that will dictate an exact method. How ever it is my hope that people will enjoy experimenting with these simple techniques and with luck find a little something of value.

If at any time you feel uncomfortable or out of control disengage your work take a few deep breaths and think about something else for a few moments. Then ground yourself.

When working with other people and energy, especially if you are sending or receiving directly make sure you know and trust the person. At least until you feel very confident and comfortable doing it. Your feelings are always your best guide if at anytime something feels strange or incorrect ask. Any one working responsibly will be able to explain to your satisfaction. Then if things still don't feel right trust your self and simply excuse yourself from the exercise, therapy or working. 

Learn to shield your self with energy, we lock our houses when we leave them so why would we wish to leave our auras open to every energy we encounter. 

Lastly energy takes practice and patience some people experience nearly immediate results for must of us it takes months to learn to proficiently move energy and a life time to get better at it.

What Crystals could I Use?

This question is often couched in terms of X says I should use this stone but Y says I should use that crystal, which should I use?
Answer: Whichever feels right to you?
There appear to be a lot of people who feel that there is one right way to use a stone and one right stone to use for various things. That's not the case. I've worked with crystals and stones and never found this to be true. If you read the better known crystal metaphysics authors such as Naisha Ahsian or Robert Simmons you'll find that they don't see this as true either, as they note multiple stones as having similar uses and energies.
It is true that certain crystals and stones tend to have energies that work well for certain things, or certain situations. Others do better for other things and situations.
To go back to the blunt metaphor, a hammer is probably easier to use to smack a nail into a board, so it's likely to be a better choice than a high heel shoe, but there might be situations where the high heel shoe is the better choice for one reason or another.
The type of stone has something to do with it. Where it grew has something else. How it was harvested and who's handled it along the way can affect it too. And the personality and energy of any individual stone also has something to do with it. There are many factors that affect how appropriate a particular crystal or stone is for any given situation.
I still believe and insist that what feels right to you is the best way to go. While I could tell you "use this, do that, and don’t do anything else" I would not feel good about it, because it's not the way crystal energy works. The metaphysical properties lore of stones is a guideline, not an absolute. Your Higher Self is the best guide as to which stone will work best for you for what you're doing at any particular time. The best advice I can give you is; listen to your instinct

NOTE:
Please be aware that Crystal Healing does not take the place of conventional medicine, nor does it replace the advice of a qualified medical practitioner. Always consult a GP for an acute or infectious condition, and problems of an urgent nature. Continue with your prescribed medication. Healing is a complementary therapy that works effectively alongside orthodox/conventional healthcare, thus expanding your treatment options.