The ability to do accurate psychic readings depends on clarity, focus, and discernment.
Accurate psychic readings are impossible to achieve without emotional clarity. Fear can stop a psychic flow abruptly; even smaller fears act as blockades and divert the attention of the psychic.
Lack of intellectual clarity distorts information and prevents accurate psychic readings from happening. The psychic's world view has to be fluid and open; the viewpoints and connections it's made of have to be integrated and well balanced.
Accurate psychic readings occur when the focus is just right - it's easy to slip and fail to see forest for the trees (overfocus) or not notice a specific tree from the forest (underfocus).
The psychic reading process results usually results in a vast multitude of information. Discernment is required to separate the wheat from the chaff - the better the psychic is at discernment the more accurate psychic readings will be.
Finally, communicating the results of otherwise accurate psychic readings to others will be accompanied by many communication flaws. Thus, as an additional step, accurate psychic readings require accurate communication as well.