Tech: I use an open-source knowledge graph system, Semantic Synchrony: https://github.com/synchrony/smsn/wiki It uses Neo4j, so it's fast and it scales enormously; it offers a true graph, not a tree; it offers full-text boolean search via Apache Lucene; it lets you connect public and private notes in the same graph, and lets you merge (some or all of) your graph with someone else's.
Choice: I believe in introspection and sharing, and not willpower. If I feel like I have to force myself to do something, it is because I am at war with myself. Instead I meditate, journal (using SmSn), do "knowledge gardening" of the earlier things I've journaled (using SmSn), try to talk to different kinds of friends, for different kinds of perspectives.
I studied economics, and it changed my life, and I recommend it to everybody. It's hard to make good decisions in the labor market, for example, without a deep understanding of it. But econ is not just about money; it's about constrained optimization generally, and applies to time management, reading, travel, love, literally everything we do.