Right now I have been kipping with a band, but my reading stresses the importance of developing the strength to do a dead-hang pullup before putting a lot of stress on the shoulder by kipping (swinging, using momentum to help propel you up and over the bar).
Keep working on your pull-ups, but make any kipping related work secondary to your dead hang efforts.
Dial it back and work on dead-hang. Engage the back. Drive elbows down. Look up and over the bar, eyes on target. Chest to bar, get full range of motion.
"Grease the groove" Work on it a little bit all the time, but never work to failure. Commitment to doing this over a long period of time will pay off. As far as negative pullups are concerned (lowering yourself slowly from the bar), the author only did a single negative per workout, on the final rep of the set. These are a high cost and can get you into muscle failure (which should be avoided).
Switch up on grips. Become comfortable in all grips. I've been very overhead-centric. Time to work on mixed-grip and underhand as well.
Somewhat interesting, not my fav of the links I found.
Really interesting comparison of resistance bands and how much they assist pull-ups. Need to measure the bands at my gym to see what a good combo would be.