This is easy. If you need to cut paper, there are two ways: or you fold it and insert your knife in the fold to separate the two parts. This method works well if you, for example, when you need the sheet you own to be cut in two identical parts. The other way works especially if you own a real and sharp paper cutter. You will need a ruler on top of the paper, with the measurements marked, and a sort of cutting mat. I once used another notebook, but that was radical. Other options are any piece of wood or thick cardboard, anything that nobody cares if it get ruined.
