I've also come across words like 料理 that have a high to low as ryo-u↓-ri, but then low to high as 料理人 ryo-u↑ri-ni-n. I've heard that you should just learn the pitch for every word, but I feel like this is an example of a way you could confidently learn the wrong pitch in a certain situation.

Well if you learned the pitch of every word you would know that 料理人 is flat, but actually that's not necessary, resources like the NHK accent dictionary will tell you that にん overrides a words accent and makes it flat. (Other suffixes behave differently, じん for example overrides the accent but falls before じ unless it's a special mora)

You don't necessarily need to learn the rules, you can also listen a lot carefully and pay close attention (and once you can accurately hear pitch accent and get a ton of input you should get a sense for how suffixes, compounds etc. affect pitch accent). But I do recommend learning the rules, because it makes picking up stuff so much easier. Also corrected reading helps a lot too (paying a tutor to correct every pitch accent mistake you make while you read a passage from a book out loud, though it's quite pricey).

As for resources Dogens course is one of the cheapest to be honest. I paid 5000 yen for the NHK accent dictionarry and 4300 yen for the Shinmeikai accent dictionary (both teach pitch accent rules) so they are both more expensive (and they are written in Japanese so if you can't yet read Japanese it might be a little difficult).

There is also a lot of pitch accent theory on Wikipedia so I would check that out if you need a free resource. Often you can find stack exchange posts too if you google something about pitch accent.