as a newbie my self, time on the machine and practice wasting parts will help bring down the tolerances. Spend some time on testing. The first 6 months I had my machine running I was doing more fixing and adjusting the machine vs making something.
Everybody will say the same about setup.
I've tighten everything I can for backlash, now it's more stopping and measure and reset 0, cut do the same again,even more so when you get to the critical measurement.
Slow going though. A long way to go.
Dave