All methods target different groups of muscle more or less. If you can only do negative pull ups. Grab a chair to put your feet on to assist as needed. Or have a partner hold your ankles as you do pull ups and you can press with your legs when you need assistance.
Start by doing negatives where you lower yourself as slow as possible for 20 secs
Once you can do one pull-up. Do one, take a break, do another and keep doing that until you can’t. Then switch back to negatives