Home Projects: Hanging Pictures

I know this sounds corny, putting up a post about hanging pictures. But there is a skill behind this. To get these pictures lined up just right, I've noticed that different people have different methods of doing this. Mine happens to be a tape measure. I literally measure where I think every nail should go. Then I nail it up (two for each picture). I hang the picture and then check it with a level, but across the top and down the side. Works for me.