Headband on Naella has pillow-shading and the black outline contrasts with the skin too harshly
You forgot to remove some of Karel's face from Zev
Red's jaw is too aliased (please look that term up it will save your ass in pixeling so many times)
Part of Zev's jawline needs to be erased (I can show you if necessary)
I suppose the splices are pretty clean, though, all in all.
I'd recommend, instead of copypasting the parts on, to put them side by side and attempt to copy them onto whatever base you want to use manually, because that'll teach you a lot about how it's done. Only if you've got a ton of spare time, though.