The fastest way to improve your life is to learn to make better decisions. There are three steps to making better decisions.
Gather enough information to increase your odds of making the correct decision. When doing this, remember the 80⁄20 rule and weigh the cost of delaying the decision vs the cost of being wrong.
Find common patterns in your decision making and turn them into principles. Simplify your decision making process to a level where anyone can take your explanation and make the same decision you would have.
Use algorithms where possible. Once you know how you make decisions, relying on computers to make them for you. They can make decisions faster and more reliably than you ever could.