Use Crayola. These are the best and have the best color saturation. Use a paper that will grip the color evenly. I like Stonehenge or illustration board. Have a good hand_held sharpener handy. Always try to keep a point on the crayon. This makes it go on more evenly. Apply the crayon in a professional manner. Just like you would any other fine art tool, use control and be deliberate. Don't become five years old again!
There are lots of ways to tint your fabric for embroidery, with the most common being crayon tinting. In this post, you'll learn a few methods to try. With all of these versions of tinting, it's best to add the color before you start stitching. While it's possible to add the tinting after your embroidery is finished, it's much harder to color all the way up to the lines and without getting markings on your thread.