Insert the trimmer into your nostril, being careful not to touch the sides of your nose. Now gently move the trimmer to the side, going in a circular motion, still being careful not to actually touch the sides of the nostril, but just skimming to gently cut the hair. Repeat on the other side. With a mirrior, inspect the nostril, checking to see that all hair has been trimmed. Repeat if necessary. Clean the trimmer after every use. The most common nose hair trimmers have either an oscillating or rotating steel blade to trim the hairs. They all feature some sort of guard to keep the blades off of your skin. Generally speaking you just need to run the appliance around the opening to your nostrils until all the visible hair is removed. Of course, you should read the instructions to your specific model for special safety instructions or extra features.