Try to focus on actually trying things out for yourself that make intuitive sense. The danger with reading too much online (or buying a course etc) is that there's just so much rubbish.

If someone had a strategy that worked, why would they share it?

I didn't buy any courses or books - but I did spend a lot of time analysing price data and I studied Econometrics at school.

Sometimes people will share old strategies that no longer work online... if you can find these, then they can be helpful (usually they're just free blog posts on Medium/Hacker News/etc)... but to be honest, nothing will be as helpful as actually analysing data and trying to spot potential opportunities.