How did you learn to touch type?

Learned in school on a typewriter. This game https://zty.pe/ is fun (also addictive) to type faster. I enjoyed that more than other online tool where you type long sentences.

Like others here, I did a lot of learning via a game and via a typing class in high school. But one thing that helped me a lot was doing some imaginary practice away from a keyboard as well. For example, if I was a passenger in a car I would read road signs and imagine typing out the letters. Sometimes I would physically move my fingers, and sometimes I would just tense the finger involved while I imagined reaching to the appropriate key. I practiced this way anywhere I was hearing or reading words and had the spare mental cycles to do it.

I used this technique again when I switched from qwerty to colemak. You'll still need some dedicated "coursework" like a game or program, but this approach lets you fit in some extra practice over the course of a day.

Learned in high-school (typing class in 9th grade) on an old IBM electric typewriter. Didn't do much typing for the next couple of years, so my first year of college I took a "keyboarding" class to refresh my skills.

In hindsight, probably two of the best decisions I've ever made.

I have used this free tool to improve my touch typing https://www.tipp10.com/en/

Remember to look at the screen, not at the keyboard ;) Also, focus on precision - not typing speed.