How to toast cumin
Toast seeds in a skillet over medium heat, stirring until fragrant. Watch very carefully so that you don't scorch it.
I agree with nutcakes. Be sure to use a dry skillet. After it's done pour it into a spice grinder.
This method works for many dried spices and seeds.
Let the skillet get hot first, then toss in the cumin and agitate constantly for about 20 to 30 seconds. Remove immediately to a cool bowl.
Be sure that you allow the toasted seeds to cool before you grind them if you are planning on doing so to keep them from losing aromatic oils.