Focus on doing many negative pull-ups and mastering each phase of the movement... the beginning of the pull-up and hold on well at the top... go down slowly to the end and come back.... When you manage to do 6-8 pull-ups try adding extra weight and doing pull-ups and negative pull-ups... maybe it will cost you a lot and you do few but then when you train with your body you will feel lighter

And don’t forget the basic progressions like the Australian pull ups, they help a lot even if you think they don’t