In this video from Gourmet Magazine, Ian Knauer shows us how to clean and use dried chilies. Chile de arbol is the spiciest. To make a great hot sauce, boil about 40 of these with the seeds in and blend with some garlic and water. Next is the chipotle chili. You can often find these in a can but they are more potent when fresh. The larger the chili, the less heat it contains. An ancho is like a poblano. A guajillo is often paired with an ancho in a recipe or an adobo sauce because they complement each other.
When buying chilies they should be flexible, not brittle. Store them in a Ziploc bag when you bring them home. When cooking with them, dust them off with a wet paper towel. Take the seeds out of large chilies. The way to toast the chili is to heat a cast iron skillet over low heat. The skillet should not smoke. Place the chili in and press down on it. You want to wake up the oils in it, both on the outside and inside. Then put it in hot water and turn off the heat. Soak for 20 minutes and then let them dry. This adds lots more flavor.