When you're cooking something savory, you use the process to get spices to open up.
Many recipes ask you to start by sauteeing something (i.e. onions) or browning your meat. When you add and heat the oil/fat/butter in your pan, add some spices then. The heat helps them release their full flavor and aroma.
For example, when I make Italian meals, I almost always do the following:
1) heat olive oil in a skillet/frying pan
2) add crushed red pepper flakes, stir for 30 s
3) add onions, stir for ~1-2 minutes
4) add minced garlic, stir until onions are translucent (i.e., cooked)
You can use this same process with cumin, coriander, etc. It works best with ground spices (chili or curry powder, for example) or even cinnamon or nutmeg. Really, almost anything!