I usually do counting breathing, I sit in a quiet place, or lay in bed before before sleep. Make sure they are deep breaths and you are extending your belly as you breath:

I will start at 1 (inhale), 2 (exhale), 3 (inhale), 4 (exhale) up until 10. Then I go back down from 10 to 1. It is incredibly relaxing. I will do it for 15 minutes sometimes, it usually puts me to sleep.