Nothing is more key to career success than the ability to think: learn quickly, analyze situations, solve problems, and communicate intelligently.
Some of that may be hard-wired but here are ways to improve reasoning that seem, well, reasonable.
Think probabilistically. If that doesn't come naturally to you, develop the habit: When you have to make a significant decision, for each of your options, write the chance (from 0 percent to 100 percent) of occurrence for each of the major positive and negative outcomes. For example, you're deciding whether to accept a new job:
Pros: Higher salary (100 percent), better boss (70 percent), more learning opportunities (90 percent).
Cons: Longer commute (100 percent), the job is more difficult and thus you could fail (50 percent), management's ethics may be iffy (50 percent).
Then, after considering all that, make your decision on gut feeling.
Of course, no technique will lead to always making correct decisions, but your batting average will improve as will your ability to explain your reasoning. And as time goes on, you'll get better at doing cost-benefit/risk-reward analysis, often on-the-fly.
Hang out with smart people. Logical thinkers who are interested in analyzing problems. Discuss and debate matters with them. Ask questions and really listen to their answers and reasoning.
You probably won't be able to hang out with famous smart people but you can watch, listen to, and read their work. In picking who to pay attention to, remember that wisdom exists on both sides, so consider the likes of Thomas L. Friedman, Ta-Nehisi Coates, and Paul Krugman on the left and Charles Krauthammer and Thomas Sowell on the right. Draw your perspectives from such intellectuals, rather than from entertainers such as Jon Stewart and Stephen Colbert on the left or Glenn Beck and Dennis Miller on the right.
Trust authoritative biographies such as those written by Doris Kearns Goodwin (Team of Rivals: The Political Genius of Abraham Lincoln), Walter Isaacson (Steve Jobs, Benjamin Franklin: An American Life), Jon Meacham (Thomas Jefferson: The Art of Power), David McCullough (Truman, John Adams), and William Manchester (the Churchill trilogy). You'll grow far wiser if you form your views from those than if you allow yourself to get manipulated by Hollywood directors. Rule of thumb: Be at least as likely to read What Makes Great Leaders Great by Frank Arnold as to read one of the Twilight novels.
Prefer The Economist (especially note its debates), The New York Times, The Wall Street Journal, PBS NewsHour, C-Span, and yes,U.S. News & World Report over lesser media outlets.
Like to join groups? Join or start a book club, attend book store discussion events, or become a member of a public affairs forum such as the Commonwealth Club, The City Club of Cleveland, or Chautauqua Institution. If you're ready for a real challenge, join a debating society.
Be skeptical about non-rational belief systems. The supernatural, paranormal, cults, even mainline religion. You'll be a better thinker if you debate dogma than accept it on blind faith.
Keep a nugget file. Every time you derive an insight that would abet your thinking or thinking skills , keep it in a word-processing file. Review it frequently.