1)Why use one? Many folks (both men & women) find that they can soften hairs and reduce razor friction. 2)Why make it yourself? Because it is inexpensive and easy. Things you'll need; Measuring cup, measuring spoon, funnel, plastic bottle with a pour cap. (I use 4 0z/125 ml. bottles) Ingredients; 3 fl. oz skin-safe oil (such as olive, jojoba, grape seed, sweet almond, macadamia, etc.) 1 fl. oz castor oil (this adds slickness) 2 tsp/10 ml. essential oil or skin-safe fragrance oil (optional) Using a funnel, pour all ingredients into the bottle you will use. Cap & shake to mix. That's it. You have just made a pre-shave oil. Things to consider; 1) Do you have skin allergies? If you have doubts about your reaction to an oil, test on a small patch of skin and wait 24 hours, to see if you have any adverse reaction. 2)Which oil should you use? All of the ones I mentioned are skin-safe. To keep it simple, you may want to use one that you can get at a local store, rather than ordering it. You should also buy the smallest quantity possible, if you are not sure how you will like it. But, if you are a hobbyist like me, go ahead and order something, if you don't see what you like locally. 3)Fragrance safety- oils of mint or eucalyptus are kind of intense. If you are using one of these, I suggest halving the amount you add.