If you can do 0-5 normal pullups negative chin-ups will be most effective for you. It will develop your muscles and raise your endurance and strength.
Durign the negative chin-ups you'll develop your strength and endurance better than while doing normal pullups (because you would be doing only few of them). You will do more negative chinups and will work your muscles more.
How to do Negative chin-ups
• Grip an overhead bar or rings and get into the top most position of the pull-up exercise (see flexed arm hang position - arms flexed and chin above the bar). Use a partner or bench to help get into position if you're not strong enough.
• Slowly lower yourself down, taking as much time as possible, into the dead hang position (arms fully extended).
• Get back to the starting position and repeat the process.
Keep the negative chin-up movement slow and controlled.
Engage the upper body muscles to create tension throughout the exercise.