Rings are one of the best tools for developing upper body strength. Before using rings foundational strength should be developed with Pulling and Pressing progressions.
progressions - Muscle up Prep drills
Progression 1 - False Grip Inclined Hang
Progression 2 - False Grip Hang
Progression 3 - False Grip Chin Hang
Progression 4 - False Grip Chin-Up
Progression 5 - False Grip Low Chin-Up
Progression - Muscle-up
Progression 1 - Foot Assisted Muscle-Up
Progression 2 - Assisted Strict Muscle-Up
Progression 3 - Muscle-Up Negative
Progression 4 - Strict Muscle-Up