To mix slush mix, start by adding the desired amount of slush mix powder to a large container. Then add cold tap water or juice to the container, following the mixing instructions provided on the packet. Stir the mix vigorously for several minutes, using a large spoon or whisk, until the powder has dissolved completely. Once dissolved, pour the mixture into a slush machine or place it in a freezer-safe container, cover with a lid, and freeze until it reaches a slushy consistency, stirring occasionally. Alternatively, you can also use a blender or food processor to create a slush mix using ice cubes and your favorite beverage, such as juice or soda.