This butterfly photo is one of my favorites! One of my first colored pencil works with prismacolor pencils was done of this species of butterfly.
One thing I learned from that project while watching everyone do theirs: do not burnish with white or those awful blender pencils! It ends up looking chalky, or thin. To get rich layers of color, well, layer rich colors!
Saw too many people put down thick color right off. Not a good idea because you will have to put down thicker color to blend. Put down many layers of thin color and you can add dozens of colors to the space giving a luminous, thick, sexy quality to the drawing. Ok, sensuous was the word I was going for, but good drawing and good use of color is sexy!
And white. White isn't a nonentity. If you add it in top of a layer of good color to "blend" it, all you will have succeeded in doing is putting it behind milky glass. Not good. I've found taking colors and just layering them may take longer, but the difference between using white or a blender to blend and layering pigment is the difference between looking through a bathroom shower door and looking at Chartres cathedral windows!
I might do more tips on colored pencil soon. Just so I can stop going into art stores and hearing "I'd buy those colors but they're so expensive it's not worth it!"
... Um. Yeah. I wan to teach people how to really work with prismacolors! And to find the right type of pencil that works with their style!
I like using different brands of colored pencils, but I can't use them in the same ways! I have to adjust my decisions based on what the pencil can do! Asking a pencil from Freds to do the same thing as a prismacolor will just frustrate you and annoy the hell out of the pencil!