To use a cast iron grill pan, first preheat over medium-high heat. Once hot, place food on the ridged surface of the cast iron grill pan and let it sear and develop those mouth-watering grill marks. It's important to avoid overcrowding the cast iron grill pan, as this can prevent proper browning and cooking. Additionally, using a spatula or tongs specifically designed for use with cast iron cookware can help protect the sauce in the cast iron grill pan.