An exacto knife is a very sharp and precise cutting tool that is often used for detailed work on paper. When using an exacto knife on paper, it is important to be extra careful and use a light touch so that you don't accidentally rip or tear the paper. First, start by lightly scoring the paper with the blade of the knife to create a line that you will then follow with your cut. Next, slowly and carefully run the blade along the scored line, applying even pressure as you go. If you are making a long cut, it may be helpful to use a ruler or other straight edge to guide your blade. Once you have made your cut, be sure to dispose of the blade safely so that nobody gets hurt.