Good Habit! That way you rather model than sketch and you get a lot more life into your creations! It is a matter of preferences, of course, but there's a lot to it not to do sketching first.
However, you can absolutely do sketches with Verve, too. Just take your brush size down, maybe even use brush 1 or 6, if you want it cleaner or 8, if you want a pencil feel. Play with opacity and build-up to find what feels best to you.
Cyan and Magenta should give blue in additive color blending. In subtractive blending it would probably end up some muddy blueish tone as well, I'd imagine. But chemistry plays a role there, too. Blue is a prime color, so ordinarily you couldn't quite produce a blue with two other colors. Just like Red or Yellow, if I'm not mistaken. However, this is the magical world of digital art... so you can do that here!

Frog looks great, but I think my eyes are losing power on some rods right now, hahaha...