I think it is important to discuss safety before we go any further. Please use caution when using your essential oils. While they are not the same as synthetic pharmaceuticals, they are still very powerful.
1) Oils and plastic don't mix. Only use glass or stainless steel with your oils. Plastics and aluminum break down and leach into the oils. If you are drinking them, it is a huge problem. Now you are drinking chemicals.
2) When diffusing, your diffuser (a contract item for essential oil companies) states to use 6-12 drops. Seriously don't. They have this instruction for the vast majority of companies out there selling floral water or synthetics. Young Living is so pure and concentrated, 1-4 drops will suffice. I promise.
3) Some oils can be "hot" and some people have more sensitive skin than others. I find that babies, redheads and the elderly have the most sensitive skin. When in doubt with topical use, start with a carrier oil and a drop of essential oil. It will never hurt to dilute just a bit more, and you can save yourself money by diluting the oils to apply over a larger area. I personally use all of my oils, with the exception of oregano, undiluted. On my kids, many things get diluted. I usually follow the thought of under the age of 5, dilute if not applying to the bottom of their feet.
4) If you get an essential oil in your eye, do not, I REPEAT DO NOT, flush with water. We have all been there. You won't go blind. I promise. How do I know...years of experience. I put five different oils on my face nightly. I get oils in my eyes several times a week. Just grab a dab of coconut oil and swipe the eyes. You will see blurry because of the oil, but the pain will go away instantly. The reason behind this: water intensifies the effect of essential oils. Want to increase the burning retinal sensation, go ahead, flush with water. Oil attracts oil. Fatty oils dilute and calm the sensation of essential oils. Trust me.
5) If ingesting oils as dietary supplements, consume with food the first few times to see if they agree with you. I take all mine whenever, wherever, but I am used to it and know my body loves them.