Hi! Thanks for the question. I have a brain injury and it's good to see there are people out there who are interested specifically in helping us.
My best advice is to read everything you can about brain injuries and their effects before you begin. Remember that although there may be "typical" effects, everyone is different and you will have to adapt your therapy for each patient. Below I've cut and pasted some helpful info from Wikipedia about the emotional effects of brain injury. I think it's pretty good -
TBI patients have been described as the "walking wounded" owing to psychological problems. Most TBI patients have emotional or behavioral problems that fit under the broad category of psychiatric health. Family members of TBI patients often find that personality changes and behavioral problems are the most difficult disabilities to handle. Psychiatric problems that may surface include depression, apathy, anxiety, irritability, anger, paranoia, confusion, frustration, agitation, insomnia or other sleep problems, and mood swings. Problem behaviors may include aggression and violence, impulsivity, disinhibition, acting out, noncompliance, social inappropriateness, emotional outbursts, childish behavior, impaired self-control, impaired self-awareness, inability to take responsibility or accept criticism, egocentrism, inappropriate sexual activity, and alcohol or drug abuse or addiction. Some patients' personality problems may be so severe that they are diagnosed with organic personality disorder, a psychiatric condition characterized by many of the problems mentioned above. Sometimes TBI patients suffer from developmental stagnation, meaning that they fail to mature emotionally, socially, or psychologically after the trauma. This is a serious problem for children and young adults who suffer from a TBI. Attitudes and behaviors that are appropriate for a child or teenager become inappropriate in adulthood. Many TBI patients who show psychiatric or behavioral problems can be helped with medication and psychotherapy, although the effectiveness of psychotherapy may be limited by the residual neurocognitive impairment. Technological improvements and excellent emergency care have diminished the incidence of devastating TBI while increasing the numbers of patients with mild or moderate TBI. Such patients are more adversely affected by their emotional problems than by their residual physical disabilities.