natural blending is a basic/intro technique in regards of how to blend with copics. 

if you're unfamiliar with how the copic color system works, please check out my page for it as doing this technique requires the knowledge about the color system.

luckily, the technique is super easy. :D

natural blending [step 1]

select the color family you will be using. for this demo, i'll be using the violet color family. 

natural blending [step 2]

find colors that have a matching saturation number [aka the first number]. for this one i have V12, V15, V17. note that the first number is all the same. what this does it keeps the same level of gray throughout the blend/shading.

natural blending [step 3]

now select the second colors that have sequential value numbers [aka the second number]. unfortunately, i don't have too many violets, so the markers i have are already sequential. you want to make sure that the value number isn't RIGHT next to one another [aka V11, V12, V13...etc]. those tend to be much closer in value so the difference in regards to shading won't be very visible. [unless you want the shades to be extremely subtle, i suppose.] what you want to pick is numbers that are about 2-3 away from one another. any further and the value difference will be extremely significant, and you won't get as nice of a gradual and soft shade change and you would like.

that's it! :D this is the basic for natural blending. there are several different techniques that actually stem from this that will give you more depth in regards to shading as well. you can find more stuff on my tutorials page. :D