Negatives can help get you there if you really want to pull the trigger. Just be careful - door frame pull up bars can ruin your door molding.

Buy the bar!

You can start by just hanging there or trying to do a pullup. Over time you'll get it!

Pushups also help to strengthen your back muscles, which helps with pullups.

It took me a solid 6 months from "never worked out a day in my life" to "can do a pullup".

I started just hanging from the bar, then moved to using a stool to get above the bar and lowering myself as slowly as possible.

Eventually, with practice, I could start holding myself in place with arms bent, then finally start moving upward.

It was a journey, but I'm glad I did it!

Look up "greasing the groove" for pullups. As others have said, an absolute beginner would start with negative reps - jump up to the top of the pull up, then let yourself down slowly.

There's lots of ways to get past the hurdle of the first pull-up! Don't psych yourself out, pull the trigger.

There are some training plans out there to get you from "couch to pullup". The trick, essentially, is to start from the top and lower yourself down as slowly as you can. After a while, you start to use resistance bands to reduce the weight you need to lift, and then you start doing assisted pullups. Over time, you drop the resistance until you can do a pullup! It does take some time (~6 week for me to my first good-form pullup).

I'm insanely jealous of the American Ninja Warriors who can do 30 pullups at once. I just don't see how that's possible. But maybe someday I'll get there...

Just a small tipp: Doing a pullup mostly depends on the latissimus dorsi muscle. It's about keeping a steady, stable body while pulling. Pull with your back, not only with your arms.

Another tip for getting started. Start horizontal, with your feet supported on a box. You are really doing a 'row', not a chin-up, but since part of your body is supported, the weight is less.

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This technique lets you develop power at the low end/start of the pull, which is where you need it most.

The other tips (hang from the bar and slowly lower yourself) are also very good.

When I started with my trainer 5+ years ago, one of my goals was being able to do a pullup. We never really focused on them specifically, I got up to 6, or so. The two things that really got me there, and they go together, were learning to activate my lats (pullups are as much a back exercise as an arm one), and deadlifts. They definitely don't work the lats directly, but you'll engage them when your form is good, training that activation under heavy load.

Problem is if you're thinking about a pullup bar, you probably don't have the equipment for deadlifts. Band deadlits can work, though.

You can also try a lat pushdown with a band to train lat activation. With pullups, it's easy to turn it into an arm exercise. It's harder to skip this with a lat pushdown.

You could do Australian pull-ups (i.e. horizontal pull-ups) to start building your back, you just need two chairs: https://www.youtube.com/watch?v=kbBDBkkuNac

Or with a broom put down between two chairs to build your hands grip: https://homegym-exercises.com/inverted_row_between_two_chair...

You can jump rope without the rope. I do this because I don't have much space in my garage for a rope to sling around, so I just pretend to hold the handles and skip rope that way.