One of the most important steps to becoming more rational for an average person would be to disentangle themselves from the default goals / values imposed by society or their peers. This would free up a lot of time for figuring out their own goals and developing relevant skills.

An average person could go far with instrumental rationality techniques like those taught at CFAR. Exercises like goal factoring and habit training don't require a high capacity for abstraction, only willingness to be explicit about one's motivations. For accumulating factual knowledge, spaced repetition software could be very useful.