I will add this, a lot of people obvioulsy haven't read previous posts (not just mine, but most others) which is normal on here.
Do not buy cheap versions of oils without checking what you are getting.
Check online for what and how to use, and when, Tisserand site is useful, Neals Yard used to be but I am not sure it is still a good one.
Buy pure essential oil, not a blend unless it is a reputable brand. Mix it yourself to dilute, use a carrier oil which is a vegetable oil, a decent one, thicker is best for small applications, walnut, avocado are good. If you have nothing else, a good olive oil. Not Crisp & Dry/rapeseed shite. Look for quantities/ratios online to mix.
Do not go out in the sun while using it, especially if you decide to use it neat, it can destroy your skin if used neat but can also burn you.
Aromatherapy/essential oils are potent and not to be messed with which is why some countries insist on a special qualification before a licence can be issued to practice. In this country people can take it as part of a beauty course which is really bad as they can cause harm if used wrongly. It makes a joke of those of us who studied and took proper exams over a number of years to ensure they didn't damage anyone.
Essential oils are antiseptic. All have different properties. They should not be messed with unless you know what you are doing. Sadly a lot of people have no idea, read something and just jump in. Anyone can buy them, anyone can cause damage with them, please be aware of what you are using before you go ahead.