Here is a straightforward look at this topic for Malachain.
Free online courses now cover almost every subject, from algebra and statistics to history and computer programming. The difficulty is rarely finding material but finishing it. Choose one course at a time, set a fixed time in the week for it and treat that slot like an appointment. Short, regular sessions build far more skill than occasional long ones.
Practise actively rather than only watching videos. Pause to work through examples, take the quizzes and explain each new idea in your own words in a notebook. Apply the skill to a small real project as early as possible, such as a household budget for a spreadsheet course. Sharing progress with a friend adds a gentle sense of accountability.
The most useful step is usually the first one. Pick a single suggestion, try it for a couple of weeks, and then decide whether it is worth keeping. Small, steady improvements last longer than ambitious plans that are hard to maintain once everyday life gets busy again.
It also helps to talk the subject through with friends or colleagues who have tried something similar. Their experience points out the details that guides leave out: how long things really take, which costs were unexpected, and which shortcuts turned out to be a mistake.
There is more to learn on this subject, and the linked website goes into greater depth. Treat this article as an introduction rather than the final word, and check any important decision against up-to-date, reliable sources before relying on it.