After you've neutralized the soap, but while it's still hot, it's time to add your fragrance and color, if desired. A good rule of thumb is to fragrance liquid soaps at about 2-3%. For example with this batch, that's about 3 oz. of fragrance. Add the fragrance to the soap and stir well. Likewise, if you're adding color (remember to take the amber color of the soap base into your coloring), add it a few drops at a time, stirring well.