I'm a big believer in timed sets and adhering to a set pace They keep the bell in your hand longer (which does help build work capacity).
For beginners, I recommend that they perhaps switch hands on the minute. Set a pre-determined pace. Slow for this exercise would be anything < 7rpm.. Moderate would be 8-10 reps. Try 8rpm. That is 4 reps every 30 seconds or 2 reps every 15. Then Switch hands and do another 8. If that is easy, either speed up or switch hands every 2 min.
Pace and timed sets makes you pay attention to technique and focus on each rep.
Hope that helps.