Are you trying to maintain what you already have? Or are you growing it out for the first time? A picture of what you want to accomplish might help. I don't want to be judgemental, but I can't envision a mustache with uniform 1/2 in. hair that would look right, at least to me. Usually one combs it down and trims it evenly across, often with the top of the lip.
Come at it from the side.