For beginners I would suggest either the Staedtler or Faber Castell brand of pencils. These produce significantly better results than bargain bin pencils, provide good colors and allow you to try some simple shading and blending techniques. With practice the best coloring results can even be achieved with the most modest tools!
Brighter results! Applying less pressure to the pencil will produce a lighter color, so how do you get that darker hue of the color on the page without pushing too hard? The answer is layers. Once you have mastered coloring between the lines with a nice even shade, you can take the same pencil and go back over that coloring again to provide a second or even third layer of color. Applying extra layers of color will remove some of the white grain that was missed in the first layer and bring depth to your color. Mix up the direction you color each layer to produce a smoother finish.