Study up on your natural ingredients...different oils have different vitamin contents, such as avocado and its vitamins E and F. Some oils are heavier than others, such as coconut oil. Some are more "skin-friendly", such as sesame oil. Also, each aromatherapy oil has different strengths -- rose is said to ease depression, for example. Also, you should always rub your hands together briskly, to warm the oils and bring their essences out. Always start with a tiny bit...less is more and you can always add oil.
I love jojoba oil for a carrier. As a massage professional, I really appreciate the fact that it does not leave my sheets smelling oily or rancid. Also I splashed some jojoba on my work clothes and they came clean without staining. Even though it is twice as expensive as grapeseed or other massage blends, I don't have the expense of harsh laundry degreasers or throwing away stinky, stained sheets. My clients' favorite essential oils for relaxation are lavender, Peace and Calming blend, Valor blend, and frankincense.
Aman knows what's up. Lavender oil is the way to go. There are plenty other oils that are similar, I'm just being biased because it's obviously my favorite. And actually when I was using lavender oil, I used it on a piercing infection that I had and it went away in a couple days. So, go lavender, go! It's not just for massage! Even though that's probably the more pleasurable of the two. Lol. If there are newbies reading, study up like Tamar advised; different oils do different things. And here - this is my fav website. maybe you can broaden your horizon