Practice the following progressions for transition in the ring muscle-up:
Transition Progression 1
Transition Progression 2
Transition Progression 3
Once you have nearly mastered the transition drills begin your progression to the full muscle-up in the following fashion:
Muscle-up w/o False-grip Progression 1
Muscle-up w/o False-grip Progression 2
Muscle-up w/o False-grip Progression 3
Muscle-up w/o False-grip Progression 4