When you buy a ruler, try to get all the same brand as some may be off 1/16 or so from another brand. I like Olfa. Also get the sandpaper dots to use on the back of your ruler. This keeps the ruler from slipping on the material. Walk your fingers up the ruler as you cut. Start with only a double fold piece of material until you are confident with your accuracy. Double check your measurements before cutting. Good luck!