It really depends on your personal style of learning, where you're at, and where you want to be.
For example, if you were interested in "go to the source even if it's difficult" to build a solid foundation, I'd start with Das Kapital. This would be a bad recommendation for someone who might go in a different direction and that you're trying to propagandize, but it sounds like you personally want stronger foundations and I say there's no better place to go than what daddy Marx had to say. It's a difficult read and will require some supplemental reading to know what he's referring to sometimes (e.g. The Paris Commune), but there's really no replacement for just reading the actual theory that's the basis for so much more reading, including Lenin. I can't tell you how many Marxists I've met who never actually read Marx's primary work and had just plain terrible takes as a result.
If you want an introduction to shedding some of liberalism's propaganda, here's a few recs:
Blackshirts and Reds. Parenti is incredibly efficient in creating displacing narratives while highlighting liberal - and therefore often fascist - lies about how the world works and has worked.
The Jakarta Method. To see the face of capital when the mask falls, to pose the question of why you've probably never heard of the events described, and harden your heart to social democratic incrementalism and just generally not taking the threats of capitalism seriously: they will kill us, we need to be aware and organize around having a ruthless enemy.
A People's History of The United States. Good for displacing white settler-colonial myths about the US that are still spread in US schools and US media worldwide.
Pedagogy of The Oppressed. Generally just good for reorienting your frame of mind away from a Eurocentric one, with a specific focus on education. There is a whole world of human experiments and self-organization out there and capitalism endlessly tries to flatten it into one mode with simple narratives and relationships that serve itself. This book is a good Marxist dissection of this.
It really depends on your personal style of learning, where you're at, and where you want to be.
For example, if you were interested in "go to the source even if it's difficult" to build a solid foundation, I'd start with Das Kapital. This would be a bad recommendation for someone who might go in a different direction and that you're trying to propagandize, but it sounds like you personally want stronger foundations and I say there's no better place to go than what daddy Marx had to say. It's a difficult read and will require some supplemental reading to know what he's referring to sometimes (e.g. The Paris Commune), but there's really no replacement for just reading the actual theory that's the basis for so much more reading, including Lenin. I can't tell you how many Marxists I've met who never actually read Marx's primary work and had just plain terrible takes as a result.
If you want an introduction to shedding some of liberalism's propaganda, here's a few recs:
Blackshirts and Reds. Parenti is incredibly efficient in creating displacing narratives while highlighting liberal - and therefore often fascist - lies about how the world works and has worked.
The Jakarta Method. To see the face of capital when the mask falls, to pose the question of why you've probably never heard of the events described, and harden your heart to social democratic incrementalism and just generally not taking the threats of capitalism seriously: they will kill us, we need to be aware and organize around having a ruthless enemy.
A People's History of The United States. Good for displacing white settler-colonial myths about the US that are still spread in US schools and US media worldwide.
Pedagogy of The Oppressed. Generally just good for reorienting your frame of mind away from a Eurocentric one, with a specific focus on education. There is a whole world of human experiments and self-organization out there and capitalism endlessly tries to flatten it into one mode with simple narratives and relationships that serve itself. This book is a good Marxist dissection of this.