This is more a subjective question. The best crystal to use is more subjective and so it is best to go with intuition where possible. When reviewing Crystals, thinking of the person and then feeling with your gut for a response is one way; some use a pendulum . This being said there are often common solutions.
The Crystal Table below has been compiled from such common solutions. These references should be taken as reliable guide, but not the final word.
For further reading on the healing use of crystals I suggest reviewing books by the following Authors;