Assuming that this is the US and if you have less than $25k in a cash account then you can only day trade settled cash (T+2). If you make more than 3 day trades (options and equities) in a rolling 5 business day period in a margin account then you are considered to be a Pattern Day Trader and must maintain a minimum equity of $25k in a margin account on any day that trades are made.
At the risk of sounding glib, the 'pragmatic rule' for successfully engaging in stock trading is making profitable trades, netting more than you lose. How you achieve that goal isn't going to be directly found in a series of books or resources but rather in your knitting that information together into a cohesive trading plan along with disciplined risk management. For lack of a better analogy, it's the difference between learning to speak a foreign language in a structured classroom environment versus being out in the real world and freely speaking the language.
What to do? You need to become financially literate. Start by reading beginner level introductory material. As you understand more, seek out the more complex books in areas of the market that interest you. Read everything that you can. Until you're somewhat literate, you won't have a clue what's worthwhile versus what's BS. Only then will you have an idea of what you don't know.
Understanding financial markets is like learning a foreign language. It takes time and effort, something most people don’t want to do and as a result of failing to do so, they often lose their money. Financial markets quickly take the money of the inexperienced and uninformed. There's a lot of junk on the web. Until you learn this language, you're going to be cannon fodder.