Yes.I normally cut the bonds length ways and then bond together whilst rolling between fingers to blend the colours evenly iykwim!I normally then cut more bond off again as it can make the bond thicker.
I only have 1 client that doesnt have blended tones as she had jet black hair on the cool side (her dad is Vietnamese) but everyone elses gets blended generally as i will normally colour before the consult and most heads of hair that i seem to get always throw up some amount of warmth.I find some of the extension colours just a little too flat and when i first started applying extensions i found if i didnt blend more than 1 tone i was never 100 % happy,although the clients were over the moon with it.
Cutting extension hair is totally different to cutting normal hair aswell and it takes alot of practice and patience to blend/cut them if you dont have a trained eye.
I have replyed to posts on here before many times in regard to the whole adding extensions but not being a hairdresser/trained etc and i still totally stand by that,so the best thing for you to do would be to get yourself on a cutting course.Not only will you gain knowledge but it will also make you more aware of the human hair and all that comes with working with it.
It isnt as easy as it looks sometimes x