Essential oils are generally considered safe if used externally. With that being said, you should never apply them undiluted to the skin as it may cause redness, rash, and burning sensations.
If used for topical purposes, always mix essential oils with a cold-pressed carrier oil like sweet almond oil or coconut oil. (Cold-pressed oils undergo less oxidation and are gentler on the skin than heat-pressed oils.)
A couple of drop of Essential Oils may be added to creams, lotions, shampoos or diffusers (aroma therapy) depending on the intended use.