There is so much out there that I really think it's best to find what works well for you, like something written in a style you could get into. Some punk anarchist type stuff might read cool and edgy or sound whiney to you, whereas reading original Lenin or Bakunin might sound dry or maybe you like the old timey aesthetic. Personally, I'd recommend Murray Bookchin's ideas of Social Ecology. They came out of an attempt to apply a more scientific approach to the problem of how to change society as a whole, including taking into account our lived and natural environment and the looming natural catastrophes. Bookchin tries to adopt the "best" parts of all the leftist ideologies and combine them into a framework for an ideology that can adapt with the times and with new understandings as they arise from each attempt at change.