Some aspects of stress management are easy to teach, but other aspects can only be encouraged to develop.
Quick and easy breathing exercises are a snap to teach, they pack quite a punch and are the most basic in the arsenal for teaching stress management. Time management, goal-setting and prioritization techniques are also simple in theory, however, that's not where the problem lies. Understanding something in theory and implementing it practically and consistently in everyday life are two very different things.
The critical parts of stress management are self-reflection and self-discipline. These cannot be taught - only nurtured and encouraged. A person has to find the willpower to develop these on his or her own. Therefore, the most important part of teaching stress management is providing a supportive environment where leading by example and positive peer pressure can do their healing magic.
Start slowly. Give a few tips that are easy to remember and use, and once a commitment to the process has been made, prepare for facing the difficult choices.