I've been using doTerra Essential Oils for a few years. My first purchase was the First Aid Kit, because it was the least expensive way to get a nice variety of oils at a reasonable price (I really wanted Frankincense, which can be quite pricey).
I began using essential oils for medicinal purposes, either topically or in a diffuser. I use a doTerra blend called, Breathe, to help my son cope with allergies. Also, I like to run a diffuser using 5 drops of OnGuard whenever someone in the family is sick.
Many of my yoga students enjoy and request Lavender, Citrus Blend and Peppermint. My current favorite blend is a doTerra blend called, Elevate. I use it topically on my wrists, feet, and chest in the morning and midday-- and no longer use any perfumes or colognes.
If you decide to experiment with oils, remember that everyone experiences oils differently and that others may not like the same smells that you do. Be aware that smells can trigger emotional responses and allergic reactions. Get started with only one oil, use it during various times of day, then record your observations both physically and mentally before you add another oil.