Get up on the apparatus and grab the crossbar with your palms facing toward you. Your grip should be little wider than your shoulders and your legs bent at your knees and crossed at your ankles. This is your starting position.
Begin by lowering your body down until your arms are almost fully extended. Then, raise yourself back up until the bar is past your chin.
Repeat entire movement for the desired or prescribed number of repetitions.
Perform this exercise in a smooth and fluid motion
It's important that you try to get your chin past (above) the bar on each repetition
Don't extended/lock-out your arms completely on the downward portion of the movement
Don't try to jerk yourself up
Don't drop down too fast
SPECIAL NOTES & LEVEL of DIFFICULTY VARIATIONS
To increase the level of difficulty, use a weight belt with chain to hang a weightplate between your legs and do the whole exercise weighted.
This exercise is one of the all-time classic movements. It's an exercise that can put on slabs of muscle onto your back. However, if you are a beginner, you may find it extremely difficult to do. The good news is that in time, as your arms gets stronger, you will feel this exercise getting easier and easier. Once it becomes too easy that means you should do weighted chin-ups.
The best way to start doing this exercise if you're a beginner is to do assisted chin ups on the machine (the one that has the counterweight and a knee pad that "pushes" you up). The assisted chin up machine is a great way to ease into this movement and get your back muscles activated and primed for growth.