Self Study
On at least a couple of occasions, I've taught myself a new subject.
At age fourteen, I bought a three-book set called "The Only Way to Learn Astrology" and most nights I studied them for thirty minutes to an hour before going to sleep. It was a persistent interest for years and I acquired probably a few dozen books over time, including an ephemerides and learned to hand cast charts at age seventeen.
At about age forty, a friend who already knew how to code sent me a book with a computer CD for learning HTML and CSS together. I was already a blogger and I went through the book and practice exercises on the CD.
1. Find good materials to learn from.
My friend who already knew how to code vetted my self study course for me and it was a good program. I did choose my own astrology books but I was a strong student generally and already somewhat familiar with astrology.
If you have no idea what constitutes a good course of study for the subject, try to ask around if possible and find out what people in the know recommend.
Do be aware that "different strokes for different folks" can apply here. If the basic information is the same, how it's presented can make a big difference in how well and easily you learn the subject.
2. Try to find more than one source and expect to need adequate context and background information for some things.
There's a somewhat famous story where someone memorized something for a class because it was written by Richard Feynman, a famous physicist, and what he had published was wrong. They thought they didn't really need to understand the material and this would be like a hack for passing the class without really understanding it and they learned otherwise.
If you are learning to code, you can look up HTML snippets or hex codes for colors or CSS snippets online. I primarily used the program my friend gifted me but I also had other sources, plus I was already a blogger.
3. If possible, apply the information.
For astrology, I cast my own chart and tried to understand myself. For HTML and CSS, I was using them on websites I ran.
In the programming world, they routinely recommend that you learn by doing. Have a project you are working on while trying to learn a new programming language. Don't expect to just memorize code without seeing it in action.
4. Study regularly and try to review materials before bedtime.
I studied astrology in bed at night because studying right before sleeping is a known way to improve retention. I studied astrology daily and in college I took notes in class and reviewed them at night before going to sleep.
I never crammed for college exams. I made it habit to really get to know the material in question and frequently obviously knew it cold in a way my classmates did not.
In my Classical Greek classes, I was the only one who actually understood it. Most of my classmates were reading the English translation from an interlinear Bible which had one line of Greek and below it the word-for-word English translation, which isn't grammatically correct in English.
Regular and repeated review will improve understanding and long term retention far better than last minute cramming for a test.
5. A word of warning about free internet sources.
Years ago, I completed the free online course Watershed Academy from the US Environmental Protection Agency. As far as I know, it's still an excellent resource.
When I took a required class in internet research as part of my online bachelor's degree program, .edu and .gov sites were considered trustworthy. That's no longer always true.
The current US administration is openly rewriting history with a clear political agenda and some .gov sites now have at best a loose relationship to the truth.
At one time, online content was generally high quality because it was mostly put out by well educated people, often people associated with a public university. Now a lot of it is commercialized or it's from random individuals whose background you may not really know.
Even when .gov sites were considered trustworthy, "history is written by the victors." The information from even very trustworthy sources can still be what is socially acceptable to some in-group in power, especially for topics like history which has a large social component that can be very subjective.
On 29 January 1863, a band of Native Americans who called themselves the So-So-Goi -- better known as Shoshone -- were massacred in a place just north of the current day Idaho-Utah border.
There are three monuments on the site, all from different times. The earliest tells a story of heroic White soldiers unjustly attacked by "criminal" Natives. The more recent monuments tell a story closer to reality that the Natives were the victims of a massacre.
If you can find information online you trust, it's still possible to learn stuff for free online. But you do need to be somewhat skeptical and I no longer have a nice, easy means to check that, like ".edu and .gov sites are always good!"