First of all I want to stress that I do no deal well with stress. I have a strategy that helps me, maybe it will help you too.
I have first to identify the source of my stress. It isn't always obvious. Am I stressed before a presentation because I don't feel adequately prepared, or maybe I am tired, or had to heal with my dog tearing up my favorite pillow just before I left.
Sometimes I will journal about the stress. That helps me more clearly see what caused it, how I felt, how I responded and what I can do to handle situations better the next time.
Here are the four big "A"s for dealing with stress
Avoid the stressor--learn to say no, cut your to do list
Alter the situation--express your feelings, learn to compromise
Adapt to the stressor--focus on the positive, look at the big picture
Accept the things you can't change--don't try to control, learn to forgive.
And I also want to stress that you have to make time for yourself, eat well, exercise and have fun, learn to laugh at yourself. These things have helped me deal with the stressful situations in my life.