I regularly get asked how to get that first pull up. Like "Four Stages To A Perfect Push Up" here is a progression model I use for getting that first pull up.
It's important to note that this progression model will work best for those who are at an average body weight and lack pulling strength to properly execute a pull-up. If someone is overweight, simply losing excess fat in combination with vertical pull training should be the main focus to start with.
Stage 1: Pulling Strength!
The goal here is to increase vertical pull strength. Once you're able to lat pull-down close to your own body weight for more than 5 reps, progress to phase 2. See "Strength Training - The Basics" for guidelines on how to build strength. These guidelines should be applied to all stages.
Stage 2: Strength, Skill and Range of Motion (Assisted)
Here he focus is on practising your pull-up skill through assisted pull-ups. Once you can comfortably go through the range of motion and need little assistance, progress to the next stage. You can use resistance bands or if you have access a Machine Assisted Pull-Up, this bit of kit is great at this stage but not many gyms have them.
Stage 3: Negative Pull-ups
Work on the negative (eccentric) pull-up, we turn things up a notch and let you practice pulling your own body weight. Once you can do several eccentric Pull-ups in a very smooth and controlled manner (controlling your body weight), it's time to start smashing out some pull-ups.
Stage 4: Pull-Up Progressions
Once you can pull yourself up for 8+ reps per set with perfect form, it's time to progress, consider adding weight!