How do I create mix-and-match discounts for cosmetics?

As a cosmetics e-commerce business owner, I'm looking to create more engaging promotional strategies that encourage customers to try multiple products. Mix-and-match discounts seem like an excellent way to increase average order value and help customers experiment with different items in my product line. I want to understand how to structure these promotions effectively, what rules to set, and how to implement them without losing profitability. What are the best practices for creating compelling mix-and-match discount campaigns specifically for beauty and cosmetics brands?