First, you need a place to do it. Be it playground (trust me, kids nowadays don’t hangout at playgrounds anymore. Because that requires them to run, which they forgot how to)

A doorway pull-up bar is good, too, which some brands claim to be able to hold up to 100kg. If you are not sure about that, you can always secure it lower, so if it does fall, you can still land on your foot.

I am writing this based on my personal experience. My doorway pull-up bar has been with me for more than 11 years and recorded more than 20,000 pullups. Best exercise equipment I have ever invested.

A pair of gym gloves is recommended. Bruised palms will slow down your progress.

Now, the technical.
Pull-ups require strong upper back and wings.
And these can be strengthened through push-ups.
Yes. Specifically, military push-ups, where by your elbows has to be as close to your torso as possible. By consciously squeezing your elbows and shoulder blades together, you are squeezing your wings, which is critical for initial stage of a pull-up.

Take note, too, you will be swinging back and forth after each pullups. It is perfectly normal. Take that opportunity and work on your core by counter swinging with your legs, like a pendulum.

Another way to start is with the help of a stool or chair.
Place it in front of you where you will hanging at the bar, place one foot on the stool, and propel yourself as you pull yourself up. It helps to stabilize your pullups, too.

One last thing before your first attempt; remember to breath.
From gripping the bar, engaging back muscle, to tighten core to counter swinging, it draws lots of oxygen. So remember to let go and catch some breath.

Hang in there guys, you can do it!