Color Test

I need help from all experts of colored pencil drawing!

I need some advices. How do you get a really smooth result? I've been working with layers and layers and layers on Bristol Smooth with Derwent Coloursoft pencils (aren't they suposed to be ultra smooth, easily blendable and all?) and it's still not what I'm looking for. On top of that, it leaves traces of pigment behind...to really not smooth. Is this normal?

Also, I have a REALLY hard time to get dark values. The paper becomes saturated so fast and it's very difficult (actually impossible) to add more layers.

I also tried the colorless blender. Yes it helps, but still. Or maybe it's normal I don't get a result as smooth as I'd like?

Thanks for your help.