If you want a clean and bold look for your picture, you can use colored markers for the color. It has a wide variety of colors and you can choose between fine tipped ones and broad tips depending on your needs. There are also refillable markers where you can just purchase ink whenever it dries up or loses its color. It's also an easy material to use. You just have to apply a single coat on the drawing. You can also add some more details using either a white colored pencil or a white inked pen.
Crayon Tinting. Using crayons for tinting embroidery is the most common technique. It's easy to learn and most people have at least a few crayons around. Crayons produce a bold color, but you can also work more gently with them, resulting in a lighter tint. Just like coloring on paper with crayons, varying the amount of pressure and layering your coloring creates some very cool shading. That shading gives your embroidery texture and dimension, and it's fun to use with modern or vintage designs.