This is pretty interesting reading, not all that long so please take the time. 

https://www.thesacredscience.com/2-forgotten-healing-herbs-of-christmas/

I order the NOW brand frankincense oil.  There are 2 types, so you have to read the label carefully before placing your order: one of them is already mixed with oil and is ready to use right out of the bottle (on skin).  The other is called Pure Frankincense and the label will indicate there is no added oils or anything else - just pure oil.

I use the one already mixed with oil on my face, straight out of the bottle and dabbed around my eyes.  I do this at night though because everything you put near your eyes gets IN your eyes at some point, and you don't want that happening during the daytime, obviously. 

I also mix it with solar oil and use it around my cuticles, ON my fingernails and toenails, and rub the rest into my elbows or the backs of my hands.  Solar oil is wonderful - smells like almonds and contains vitamin E, jojoba oil, rice bran oil, and of course sweet almond oil.  Great stuff.

I use myrrh oil in my toothpaste (since I just brush my gums these days!) and it helps kill bacteria.  I also use it as a mouth rinse after I brush by mixing a few drops with about 2 oz of filtered water.