Mix with**: This is used when combining two or more things together.
* Example: "Mix the flour with the sugar."
Mix in**: This is used when adding something to a larger quantity.
* Example: "Mix the spices in with the sauce."
Mix up**: This is used when combining things in a haphazard way.
* Example: "The kids mixed up the toys up on the floor."
Mix into**: This is used when combining something into a liquid or other substance.
* Example: "Mix the yogurt into the batter."
Mix among**: This is used when combining something with a group of other things.
* Example: "The new student was quickly mixed among the others."
Mix through**: This is used when combining something thoroughly into another substance.
* Example: "Mix the batter through until it's smooth."
The best preposition to use will depend on the specific meaning you want to convey.