Level 1 - passive hang hold for at least 20-30 seconds, more is better
Level 2 - active hang - pulling down with just shoulder blades (scap pullup) 20 seconds (more is better)
Level 3 - chin over bar hold - hang as long as possible with chin over bar (20 seconds)
Level 4 - pull up negatives - jump to chin over bar, slowly lower down to full lockout. Should take (2-3 seconds at least for 5 reps). Note where you drop faster vs slower (faster sections are areas for improvements
Level 5 - segmented negative - pausing during negative pullups
Level 6 - partial pullups - working specific sections of the pullup (high, med, low)