Your understanding of a art as a medium is the most important factor. Your interest in psychology; intuition, creativity, imagination, etc are also essential traits. You will benefit from good communication skills. You will benefit from a flexible and adaptable approach. You need good emotional balance, a non-judgemental attitude and ability to relate to people suffering from variety of physical and mental conditions. You should be able to empathise with people, listen to them and be able to understand the underlying requirements.