Comb the mustache so all the hairs are pointing in the same direction. Trim along the edge of the lip with your trimmer. Follow the line of the upper lip to so that you expose it evenly.
Lift the hair of the mustache gently with a comb. This will help you spot hairs that are longer than the rest of the mustache. Be thorough in this step so as not to let any stray hairs go unnoticed.
Slide the trimmers up along the teeth of the comb to trim the longer hairs. This will blend the mustache to give it a more consistent length. This provides a cleaner, more symmetrical appearance and gives your mustache balance.
Complete your grooming routine by trimming the hairs right below the nose. Doing this correctly creates a smooth line across the top of the mustache.