I can't speak for Matt, but after he mentioned this in our conversation, I started reading the book The Goal, a "business novel" which is supposed to teach you the theory of constraints. I've found it to be a reasonably good read, but I'm not sure how broad its applicability is outside of manufacturing. If you don't work in manufacturing, I think you could plausibly get a large fraction of the value you'd get from reading The Goal by understanding the ideas in this Wikipedia article.
I'm not sure how broad its applicability is outside of manufacturing
Technically, the book The Goal only addresses one application of TOC, rather than the sum of TOC or its techniques. (Certainly, the five focusing steps are generally applicable problem-solving tools.)
Most of the TOC body of knowledge is actually a set of tools for doing systems analysis and planning in group settings, based on formal cause-effect logic represented in diagram form. The details of such tools can be more readily found in textbooks like Thinking for a Change or The Logical Thinking Process. (Neither is a novel, and both are written by people other than Goldratt. Personally I find Goldratt's novels the more enjoyable reads, but they necessarily leave out lots of details you need in order to do anything besides apply the specific generic solutions they derive.)
And TOC's Drum-Buffer-Rope scheduling model (as described in The Goal) is only one of TOC's "generic business solutions" -- there are others for other aspects of business, including project management, accounting, inventory management, and even marketing. They can generally be applied without needing to reconstruct them from first principles, though the business novels that introduce those solutions will generally show a portion of the working needed to derive them.
The two thinking tools, though, that I've personally found most valuable are the Prerequisite Tree and the Evaporating Cloud. The first one is basically the idea that you can make a plan simply by listing all the reasons why you can't do something, and then turning those around to identify subgoals. (Which you can then continue objecting to, recursively!) If you are as inclined to negative thinking as I am, this is no small thing. ;-)
The second one is a method for surfacing and questioning your assumptions about the incompatibility of yours (or yours and someone else's) conflicting goals, and about the available means of satisfying your preferences. I have taught it to others as a creativity tool, because essentially that's what it is. By forcing you to clarify the conceptual relationships that lead to a conflict, it gives you a handful of specific points to question your assumptions with.
(I have used the other tools on occasion as well, and adapted some of the generic business solutions to improve business situations before, but far less frequently.)
At the 2014 Effective Altruism Summit in Berkeley a few weeks ago, I had the pleasure of talking to Matt Fallshaw about the things he does to be more effective. Matt is a founder of Trike Apps (the consultancy that built Less Wrong), a founder of Bellroy, and a polyphasic sleeper. Notes on our conversation follow.
Matt recommends having a system for acquiring habits. He recommends separating collection from processing; that is, if you have an idea for a new habit you want to acquire, you should record the idea at the time you have it and then think about actually implementing it at some future time. Matt recommends doing this through a weekly review. He recommends vetting your collection to see what habits seem actually worth acquiring, then for those habits you actually want to acquire, coming up with a compassionate, reasonable plan for how you're going to acquire the habit.
(Previously on LW: How habits work and how you may control them, Common failure modes in habit formation.)
The most difficult kind of habit for me to acquire is that of random-access situation-response habits, e.g. "if I'm having a hard time focusing, read my notebook entry that lists techniques for improving focus". So I asked Matt if he had any habit formation advice for this particular situation. Matt recommended trying to actually execute the habit I wanted as many times as possible, even in an artificial context. Steve Pavlina describes the technique here. Matt recommends making your habit execution as emotionally salient as possible. His example: Let's say you're trying to become less of a prick. Someone starts a conversation with you and you notice yourself experiencing the kind of emotions you experience before you start acting like a prick. So you spend several minutes explaining to them the episode of disagreeableness you felt coming on and how you're trying to become less of a prick before proceeding with the conversation. If all else fails, Matt recommends setting a recurring alarm on your phone that reminds you of the habit you're trying to acquire, although he acknowledges that this can be expensive.
Part of your plan should include a check to make sure you actually stick with your new habit. But you don't want a check that's overly intrusive. Matt recommends keeping an Anki deck with a card for each of your habits. Then during your weekly review session, you can review the cards Anki recommends for you. For each card, you can rate the degree to which you've been sticking with the habit it refers to and do something to revitalize the habit if you haven't been executing it. Matt recommends writing the cards in a form of a concrete question, e.g. for a speed reading habit, a question could be "Did you speed read the last 5 things you read?" If you haven't been executing a particular habit, check to see if it has a clear, identifiable trigger.
Ideally your weekly review will come at a time you feel particularly "agenty" (see also: Reflective Control). So you may wish to schedule it at a time during the week when you tend to feel especially effective and energetic. Consuming caffeine before your weekly review is another idea.
When running in to seemingly intractable problems related to your personal effectiveness, habits, etc., Matt recommends taking a step back to brainstorm and try to think of creative solutions. He says that oftentimes people will write off a task as "impossible" if they aren't able to come up with a solution in 30 seconds. He recommends setting a 5-minute timer.
In terms of habits worth acquiring, Matt is a fan of speed reading, Getting Things Done, and the Theory of Constraints (especially useful for larger projects).
Matt has found that through aggressive habit acquisition, he's been able to experience a sort of compound return on the habits he's acquired: by acquiring habits that give him additional time and mental energy, he's been able to reinvest some of that additional time and mental energy in to the acquisition of even more useful habits. Matt doesn't think he's especially smart or high-willpower relative to the average person in the Less Wrong community, and credits this compounding for the reputation he's acquired for being a badass.