Basically it starts with your interest with this matter in this type of industry and everything i knew, i got it from this forum and from google searches and also by my friends that I know. It wouldn't hurt to have a basic knowledge of economics, which was thought in school days but basically the rest would be just reading posts, common sense and a heck of a lot of google searches or youtube vlogs and reviews.
We are all starting right there reading some small information and then we dig and dig more as is the information is getting interested, while the school doesn't really teach you everything that's why we have to do it in our own way. We are so lucky today because we could just easily search everything now on the internet.