breathing deeply for 3-5 breaths makes a big difference "in the heat of the moment" when you are feeling stressed.
and then for meditation, take three minutes and gaze at a candle. when your mind wanders, gaze at the candle. listen to your breath at the same time, if possible. if you think, acknowledge the thought, then try to gaze and listen again. 3 minutes is a long time when you are first starting, so use a timer so you don't ahve to watch the clock.