Depression
Changes in sleep patterns
Changes in eating patterns
Changes in energy level
Changes in ability to concentrate
Changes in the use of drugs or alcohol
Refusal or reluctance to attend school or work
Withdrawal or isolation from friends or family
Aggressive Behaviors, either verbal or physical
Difficulty making decisions or solving problems
Chronic physical complaints without apparent basis
Self-neglect or lack of attention to appearance
Impulsive behaviors such as drag racing, driving too fast or carelessly, or drinking (other drugs) and driving
Verbal statements such as 'It doesn't matter anymore' or 'I wish I was dead'
Obsession with death, dying, violence suicide
Purchase of ropes, guns, knives, razor blades, or saving of pills
Setting of affairs in order or giving away prized possessions
Humiliating life event
Any behavior which give you cause for an 'invitation' to help someone in trouble