To change the pressure sensitivity, it depends on the tablet, but one like mine (a Wacom Bamboo) usually has an installation process that puts some addresses in the home button, like "Configuration". In there, it's just a matter of playing with it until it does satisfy you.

As for the Gith, I can't find anything other than a normal humanoid (of course, excepting the nose and cheekbones). It's a normal humanoid, you could simply add the shape of cheekbones to the face, so it looks like it's really thin.
Other than that, I have nothing to suggest, unless we're talking a different thing I didn't find about.