I’ve been doing pull-ups and push-ups since preschool, I’ve never lost the ability and have no memory of how I learned it. In lack of personal experience, I had to search for methods on how to coach others. My favorite method I always use on clients I learned from youtube clips with coach Alexandra Bernardin, now at Kilo Strength Society.
The routine is based on excentric work. Even if you’re not able to do one concentric repetition (pull yourself up), you can probably hold on to the bar at the top and slowly lower yourself down. Which is exactly what you’re going to do now.
First step: start every repetition at the top, lower yourself in a slow controlled manner with a 10 second tempo. That is, 10 seconds from top to bottom without any pauses. Do as many repetitions you can in this tempo (10 seconds). As soon as you cannot hold the 10 second tempo, the session is over. When you manage at least 3 sets of 10 repetitions, you’re ready for the next step. Alexandra recommends 15 repetitions, but I’ve found that 10 reps usually is good enough. There’s a small issue of boredom involved here.
Most clients of mine start of with one set of three repetitions, but the reps go up very fast so don’t be struck with disapointment. Be patient. Do this routine twice a week, and you’ll see progress every week.
Second step: start from the top, hold a position short of full flexion for 10 seconds, lower yourself half way down and stop, hold that position for 10 seconds, lower yourself to a position short of full extension, hold that for 10 seconds. Start over. Again, do this routine, twice a week, until you manage 3 sets of at least 10 repetitions.
Third step: you should by now be able to do at least 2 or 3 repetitions of a concentric pull-up. Do as many as you can, and aim for one more in every session until you hit your target.
Here’s the video clips I learned from. They also have more recent clips made at Kilo Strength Society. Check it out.