I am currently studying Pre-Calculus on my own. I have a few texts I am working with but feel like I could learning a lot more than I am. 

When people typically ask these kind of questions the common response for Pre-calculus->Calculus is to watch "Khan Academy" etc.

Is this really a wise approach, especially when confronting future topics? Wouldn't it better to develop more independent, self-sufficient learning strategies beforehand?

I always wonder how mathematicians teach themselves so much knowledge without resources like "Khan Academy", lectures or even teachers. People learned math before the internet, what was the strategy then?

Some other questions:

* Which is the better source to learn from, video lectures or reading the text? I feel like video lectures are too passive. Would time be better spent doing more exercises and less video lectures?
* If you watch a video lecture, should it be watched before reading the text or after?
* Math is quite concise as presented in textbooks, is summarizing the chapter as you read in a notebook effective or unnecessary?
* Should I completely read chapters before attempting exercises or try questions first and refer to the text as needed?

Final question:
If a person was attempting to learn a topic in math from scratch with minimal knowledge on the content, what is an approach they could apply to learn it that would be both effective and efficient? 

Thanks