Often will you hear me say you mix something with a carrier oil.  What in the world am I talking about? 
A carrier oil is an oil you use to mix with your essential oil before you add it to your skin or before taking your oils internally.  It dilutes the oils and carries them, AAAH, onto your skin (or into your tummy!)  When you are first starting out always use a carrier oil until your skin is used to your essential oils, and your stomach gets used to them to!  Always use a carrier oil on your littles (that is what I call my kiddies!)
I've tried a few different carrier oils.  I use whipped coconut oil (by whipped I mean using a hand mixer to whip coconut oil for around 5 minutes until it is creamy like frosting), jojoba oil, argon oil, almond oil, & avocado oil.  You can also use grape seed oil, olive oil, & other nut oils.  Oooh and there are so many other oils! 
I have very sensitive skin so I stick to organic oils, as I don't want any icky stuff on my skin, or at all in my tummy!  That is a personal preference though.
Not all carrier oils are going to work on every person.  Some may irritate your skin.  Start with a small size bottle when you order, just in case! 
Why do I have so many different ones?  Well I'm still playing around figuring what I like.  The jojoba is amazing on my face!  The whipped coconut is my favorite for the pain concoction. 
I also like to make mixes of my carrier oil with my essential oil, like this stress away.  I took an empty bottle of stress away, added 2 ml stress away and 2 ml argon oil with a roller cap!  A quick shake and it is always ready to use.