I was told by my instructor not to do compass turns...just do timed ones instead. 3 degrees/second = rate one. They can be done though and this is what I was taught:
If you undershoot when turning onto northerly headings by 30 degrees and overshoot the same for southerly ones then they usually work out OK. Just remember to always give the compass time to settle and also that when you look at a W compass you have to turn away from the digits to get to them.