Reading the emotions of others:
The ability to pick up others emotions is something we can all do naturally. The fastest way to learn to be sensitive to and identify others emotional states is to learn to read our own. If we cannot inwardly read and identify our own emotions it will be impossible to do this for others.
The great danger of getting too close to others emotions is that we fall into them and create the same emotions ourselves. This is often seen as one of the pillars of friendship in an emotional relationship. But to fall into and create and experience the same emotions as another is not sympathy (mercy), and it doesn't help them climb out of their disturbance. Hence the need to practice 'detached involvement', a process in which we stay sufficiently detached to be able to accurately read and understand the emotions of another while staying sufficiently involved with them so we may offer our help to them.