Of course, to do so, they use pencils and have erasers handy when they're working. While some of the stitchers preferred to use a regular black pencil and draw their designs with a symbol assigned to each color they use, others like to use colored pencils so they have an idea what the completed design will look like. The majority of those who use colored pencils color in the squares on the graph paper. The only fault anyone at chat found with using colored pencils is it's often hard to find as many colors as one may need to complete a design. The widest array of colors in pencils I've ever seen has been at art stores in my area.
Graph paper comes in a variety of grid sizes.
Some has a heavy line every 10 squares, while other graph paper doesn't. The stitchers at chat said if their design is too large to fit on one sheet of graph paper, they tape the sheets together. I've found rubber cement a good adhesive to use when I've had to attach several sheets of paper to each other. For me, it's easier to handle than is tape, and it doesn't have the stiff consistency of some other glues I've used. Once again, a matter of personal preference.