You need to take action and learn from the mistakes
Knowledge come only from experince.
Knowledge doesn't just come only through experience, you can gain it through learning. How would you prefer to make mistakes when you can learn from other people's experiences? You cannot underestimate the benefits of learning from books and experienced people. It would be unwise to venture into a business or career without doing in-depth research about such an endeavour. It is good to start and make mistakes as you engage in the activity but you can reduce mistakes by learning from others through books, tutorials and other mediums.
Index investing and DCA is the best that the majority of people can do to become more wealthy. But this only works if you have big enough income
These are your views. There are other viable means of making money besides the mediums you have listed. DCA works perfectly with people who are also low-income earners. All you should do is keep some funds aside weekly or monthly based on your capacity.