You can wax your armpits without making a lot of preparations, but if you take these measures the experience will be less painful and more effective:  Clean your underarms thoroughly. Wash them with soap or a good body wash, and scrub them a little to exfoliate the skin. If you use hot water, the hairs and surrounding skin will soften, making the hairs easier to remove. Trim the hair. If the hair under your arms is longer than 1⁄4 inch (0.6 cm), you should trim it with a pair of barber or nail scissors until it's 1⁄4 inch (0.6 cm) long. This makes the waxing process less painful. The wax is bound to spill and create a mess when you try to do it yourself, so it's best to be either naked or wrapped in something you don't mind getting impregnated with wax. Make sure you use wax that is intended to be used to remove leg and body hair, rather than wax intended for use on the face. Follow the instructions on the package and heat the wax in the microwave or in a wax heater. It's ready to use when it's completely melted and runny.  If this is your first time waxing, do a test on the back of your hand, where your skin is less sensitive, to make sure the wax isn't too hot. Body wax kits are available at drugstores and beauty supply stores. You can make your own sugar-based body wax using the following recipe: mix 2 cups of sugar with 1/4 cup water and 1/4 cup lemon juice. Heat the mixture over low heat on the stove until the sugar dissolves and becomes a sticky syrup. The mixture is now ready to use.

How would you rephrase that briefly using Chinese?
脱毛前处理腋窝。 用一只旧毛巾裹住身体。 加热脱毛蜡。