For those flying coaxials and most anything with no locking gyro, I ask them to try removing the rudder spring entirely. That way tail corrections happen without thinking about it. Ya just drive the tail like you do the throttle. And yes, until you get the thumb action figured out you will get some rudder with throttle. That's why we practice.
I run all of my sticks really loose - just enough to tell me where center is. That's for land based, airplanes and helicopters.