Use the top of your fingernails.
I have the Xenarc 7" touch screen, but it requires a fair amount of pressure to register a touch. This isn't really an issue for just pressing on-screen buttons, but when doing gestures, it's difficult to do a fast clean stroke without big gaps. I tried to find a sensitivity setting in the supplied driver, but no luck. Anyone know if there is a way to increase the touch sensitivity on these screens?