I need your advice on how to study history better as an amateur. What are the sources that I should follow to improve my skills on the metalevel? What skills would you recommend that I focus on in the first place? My intention is to become a better amateur historian, by which I mean to improve my general ability to learn history or to learn it in a less amateur way. I currently believe that it's possible without formal academic training, but I wouldn't mind a solid curriculum to follow on my own.
I have a degree in Philosophy, so the study of history is not wholly unfamiliar to me. I read scholarly books and articles, but when doing so, I often feel like I could get more out it — if only I knew the methods and tricks that some of you are familiar with as less amateur than myself.
Generally, the more time you spend reading and learning instead of worrying about your methods the more you will learn.
Aside from that, when facing a historical text, alwqys try and figure out what the author is trying to tell you, what their argument is. Think of it as a conversation between you and the author, and try and understand their argument, why they are making it, what evidence they are giving to back it up, and what evidence is there to the contrary. To get a deeper understanding of a particular subject or time period, you can compare the arguments multiple authors make, see where they coincide, where they differ, and draw your own conclusions/opinions.
For recommendation on specific subjects, this subreddit has a wonderful wiki with a book recommendation list broken up by region and time period
Aside from reading lists compiled by reputable historians/organizations I want to offer another path.
You could always practice your skills on some Stanford History Education lessons. They are built to improve history skills and you will learn a ton of info. It'll be more of a set of lessons on how to think like a historian before you begin your journey into exploring history through different contexts.