Lavendar Essential Oil is a calming scent. I mix it with Epsom Salts and put it in a beautiful container near my bath. The oil suffuses into the salt and when you need a luxurious soak, add about 1/4 cup to the hot bath...mmmmm... you will feel so relaxed!
Ditto everything kekecat said. Lavender essential oil should be in everyone's arsenal. I like using a combination of lavender and tea tree oil on pimples--as effective as over-the-counter stuff loaded with chemicals and preservatives. I also add a few drops to baths and massage oils and use it to scent my linens when I'm ironing.
I always have some Lavender essential oil kicking around my home and that's because its bloody marvelous! Its a brilliant all rounder - has antibacterial properties so great for skin care. Great on burns and other minor wounds and smells delightful. I could list all day but I won't so just google it. My personal use is for on the spot treatment and rubbed on temples to stop a headache - doesn't stop migraines though!
Aromatherapy is a bit challenging so this is a great starter oil and does just about everything. It is a dryish oil in that it isn't too greasy and absorbs quite quickly. Lavender is also one of the few oils that can be used neat on the skin, however if you have very sensitive skin I suggest diluting it with a base oil for safety.