How many times have you been playing in lessons when your teacher points out a mistake that you didn”t even know you made?
For this practise method you need to start each new piece or section of your practice (ie scales,study, technical excercises) by playing very, very slowly through the music ” the slower the better. This will give you the chance to notice every little thing that you need to improve. Listen very carefully and play very slowly.
Once you have been through the slow listening phase you can then continue to practise as normal making sure to address those areas highlighted by the slow runs throughs.