Acrylic and fabric paints have a more intense color. These paints dry fairly fast, but you can mix and blend the color if you work quickly. The paint stays mainly on the surface, so if you work with a small brush, you can paint crisp lines right up to the edge of where your embroidery will go.
Practice by shading two contrasting colors into one another. For example, take your red pencil and your green pencil. Starting with the red pencil, shade from left to right, dark to light. Next, take your green pencil and shade from right to left, dark to light. Work on blending them as seamlessly as possible where they meet in the middle.