Fill a small spray bottle with distilled water and add 80 to 100 drops of essential oils blend of your choice.
Here's what I use for a real calming effect: 20 drops chamomile essential oil, 50 drops lavender essential oil, and 10 drops rosemary essential oil. I find the chamomile tends to overwhelm the other smells, so it might be worthwhile to start with just 10 drops and increase until you are pleased with the fragrance.
Another favorite blend is this one: 20 drops Thieves, 50 drops lavender and 10 drops Frankincense. No matter what, I choose lavender, I just love its soothing effect on me!