I suggest you to watch as many football matches as possible and also listen to good pundits. Understand each football position, what are their duties, how they play, learn football formations, learn team strategies, watch tactical breakdowns. When you see a match between PSG VS Barcelona for example, learn their players, how they work, how their managers work, how they make choices, what mistakes they make, how they attack, how they counter-attack, how they defend and so on.
You can watch some live football games on some casinos for free but if you are looking for an app to legally watch live football games, you have to pay monthly subscription. It also might be a good idea to use ChatGPT to get a quick summary or analysis of matches.
This is one of the ways to get a better understanding of the sport you are going to bet on. Watching all the matches is very difficult, so at least you should watch extended highlights of the games played by the teams you follow the most. There are also statistical indicators that help evaluate how a team performs during a match. In fact, there are a lot of materials available for analysis nowadays, but apart from watching games you also need to take many factors into account, such as the lineup, injuries and even any news, conflicts within the team and so on.