Here are some common soapmaking additives that you can use when soapmaking. The usage rates are provided as a suggested starting point. You can use more or less depending on your desired result.

AdditiveUsage RatePurposeHow to Add to Soap
Coffee Grounds1 tablespoon per pound of oils, use more or less depending on desired amount of exfoliationExfoliation & colorYou can toss coffee grounds in lye water to pull out color or simply add to oils before mixing in lye solution.
Orange Peel Powder1 teaspoon per pound of oils, use more or less depending on desired amount of exfoliationExfoliation & colorAdd to oils before mixing in lye solution.
Beeswax1-3% of total oils, too much can make your soap draggyAdds hardness to soapMelt it with your hard oils and butters.
Oatmeal1 tablespoon per pound of oilsOatmeal is wonderful irritated and sensitive skin. Oatmeal is also an exfoliant. Powder in food processor for less exfoliation. Add to oils before mixing in lye solution.
Honey1 tablespoon per pound of oilsHoney increases latherAdd to warm oils before mixing in lye solution. Can cause soap to accelerate or overheat.
Cocoa Powder1 tablespoon per pound of oilsNatural colorantAdd to warm oils before mixing in lye solution.
Clay1 teaspoon per pound of oilsNatural colorant and light exfoliationAdd to lye water to draw out more color. You can also add to traced soap if swirling.
Poppy Seeds1 teaspoon per pound of oilsExfoliation and speckled appearance Add to oils before mixing in lye solution.
Sugar1/2 teaspoon per pound of oilsLather boosterAdd to warm lye solution.
Salt1/2-1 teaspoon per pound of oilsAdds hardness to soapAdd to lye HOT lye solution to dissolve.
Corn Meal1 teaspoon per pound of oilsExfoliationAdd to oils before mixing in lye solution.
Ground Dried Herbs - Spearmint, Peppermint, Rosemary1 teaspoon per pound of oilsExfoliation, most turn black/brown in soapAdd to oils before mixing in lye solution.
Dried Flowers - Lavender, Rose Buds, Calendula1 teaspoon per pound of oilsExfoliation, most turn black/brown in soap (calendula stays yellow, lavender ends up looking like mouse poop)Add to oils before mixing in lye solution.
Silk Fibers1 pea size pinch per pound of soapmaking oilsSlip and silkinessDissolve in hot lye solution
Activated Charcoal1 teaspoon - 1 tablespoon per pound of oils (depends on how dark you want your soap)Natural colorant - gray to blackAdd to oils before mixing in lye solution.
Aloe Powder1/2 teaspoon per pound of oilsSlip and silkinessAdd to oils before mixing in lye solution.
Milk Powder - Goat Milk, Buttermilk, Coconut Milk1 tablespoon per pound of oilsCreaminess and lather boosterAdd to oils before mixing in lye solution.
Seeds - Apricot Kernel, Blueberry, Cranberry, Raspberry1 teaspoon per pound of oilsExfoliation and speckled appearance Add to oils before mixing in lye solution.
Sodium Lactate1 teaspoon per pound of oilsAdds hardness to soap, can make soap crumbly if you use too muchAdd to oils before mixing in lye solution.