Be aware that ALL essential oils, with the exception of Tea Tree and the whole Lavender family, need to be diluted in a suitable carrier oil before applying to your skin, or, as Crux has noted, you will burn your skin.
Tea Tree and Lavender you can use neat. Not any of the others. Even when using ess oils for perfumes, you still use a base oil to dilute them and make them safe for topical use.
You can sprinkle neat essential oils onto a cotton hankie (they evaporate very fast from tissues) and inhale them, or on your pillow, across the top of your bedding near your head, or use a room diffuser.
You can add up to ten drops to a bath, or add 5-10 drops to 10-25ml base oil to massage into your skin.
I add Lavender into a sinkful of water, squeeze a flannel out in it, and wash myself with that. It's amazing how much grime comes off! I don't use showergels or shampoos anymore (nor commercial toothpaste - I make my own with fine ground sea salt, bicarb, and essential oils. Clove, peppermint, spearmint, oregano are all good for taste and dental health). Essential oils don't have SLS etc, and they smell delicious.
Hope that helps with ways of applying essential oils.