I'm learning and learning to learn economics too. If they're not a primary source for learning, I still find textbooks useful as references. A detailed table of contents and explanations of each concept can be useful when concepts or explanations are omitted from another source. And, if you don't mind reading textbooks cover-to-cover, they tend to be complete.
Here are some free online economics texts. Other commenters are suggesting micro before macro, so go with that. They should all be useful for optimizing the world in specific ways. Reading the introductions of more advanced texts should tell you about how the field is divided and may guide you to realize what you want to study in particular.
I would like to learn more about economics but I don't know where to start. Can lesswrong suggest specific areas of economics that are particularly useful for understanding and optimising the world? Specific suggestions such as reading lists and resources would also be much appreciated.