Remember to breathe! Exhale as you curl up, inhale as you roll down.
SETS & REPS
Experiment with 5 reps then rest for 30 seconds. See how you feel. Then 3 reps and rest, then 1 rep and then finish. If you feel fine the next day, add a rep to each set. You can continue to increase the reps as long as you feel comfortable and pain free doing so.
If you have no leg pain, alternate the leg which is bent. If you have leg or buttock pain, bend the knee on the painful side.