I think of both telepathy and empathy in terms of physics; wavefronts, to be more precise. Intensity, amplitude and frequency makes each psi pattern a unique signal. In a crowd, several signals can amplify or damp out each other.
Empathy, like heat, decreases with distance. Telepathy does not, but as the range increases, so does the white noise and it becomes more difficult to pick out a single signal. Empathic shielding are basically blocks, telepathic shielding more sophisticated filters, allowing specific signals.
Telepathy is an exact science. The telepath tunes in to the other mind and interprets the patterns, by adapting the same brain chemistry with a time-lag. This is interpretation, rather than reading, because the telepath can't know what the other person is thinking, s/he can only know what s/he is thinking when the same things are going on in his/her brain. The major brain areas involved are the frontal cortex, temporal cortex and hippocampus.
An empathic signal is much more difficult to decode. There is input from the whole peripheral nervous system, the amygdala and the limbic system. Pheromonal and hormonal states add to the complexity of the signal. Empathy emulates an emotional state through modulating hormone levels and the response involves the whole body.
Opening and maintaining an empathic or telepathic link is like picking out a radio frequency and staying in tune with it. Some frequencies are easier to predict and chart than others; familiarity would help. A constantly maintained link works like an open channel, at worst it is a distraction and a drain, at best it is an anchor and a source.
Telepaths and empaths have some features in common. They both tend to act as mediators in their efforts to tidy up their surroundings. It's difficult for them to handle conflicts and to hold their ground, since they can see their opponents motives as clearly or clearer than their own. They constantly broadcast their subconscious wishes to their surroundings. They aren't conscious of doing it, or if they are, they don't realise to what extent they are doing it. In restaurants, the waiter comes up to their table at once, in traffic the other drivers let them switch lanes without a hassle, and as a rule, they can have love or at least attention.
They are aware that others are thinking and feeling, but mostly because their power reminds them. They use feedback and feedforward responses to formulate the appropriate answer. If the feed is blocked for any reason, their behaviour becomes based on their own internal rules, provided they have any.
They are extremely self-involved. To maintain some degree of normal social functioning, they need to be in full control of their power, so they are constantly monitoring themselves. If their control slips, they revert to stereotypical behaviour as a safety valve: telepaths turn cerebral and obsessive-compulsive, the empaths become emotional and unstable.