Besides the international frameworks, it depends on the legal system in your country. My recommendations might be a little bland from right here on the treadmi

Besides the international frameworks, it depends on the legal system in your country. My recommendations might be a little bland from right here on the treadmill; but pick up introductory college textbooks on the three subjects. They will go into the overall topics and important legal principles. Also read case law as the books suggest, some are really kind of funny. At least to me. I actually found law surprisingly useful and enjoyed those courses at uni. Maybe because I studied so little of it, or maybe because I should have gone all the way into that profession. Protip: As an individual, drop a few legal paragraphs into a well written complaint when you've been wronged, and in my experience 9 times out of 10 the business will relent, instead of going further into legal matters.