Learning without bounds is a fundamentally different kind of challenge.

A good analogy comes from computer science. When searching for something, there are two strategies we can use: depth-first or breadth-first.

Depth-first works by picking one direction and going deeper and deeper. When that path is exhausted, we then back up to the start and begin digging again.

Breadth-first works by fanning out. We first explore our surroundings. If that doesn’t work, we pick one direction and fan out again.

If the space we’re exploring is bounded—like a fenced-off backyard—both approaches will work. Eventually we’ll cover the entire area.

If the space we’re exploring is unbounded—like a vast open plain—this equivalence breaks down. Now, going depth-first, we may head down an infinitely long detour and never find what we’re looking for.

Learning is similar. With a list of topics to learn, and the expectation that we need to learn everything on it, then the path doesn’t matter so much. Anything that covers the entire syllabus will do.

But if we’re learning outside a finite list, for life, different strategies can have wildly different results. If we choose poorly, we might get stuck on a path that never leads to our destination.

If the goal is to learn everything useful that could help us grow our business, all the computer science concepts that will make us a better programmer, the words and phrases that let us communicate in a new language—all unbounded topics—what strategy should we use?

In general, we want to learn the most useful, basic and broadly applicable ideas first, only moving onto the esoteric, advanced or specialized later.

But putting these abstractions into practice can be tricky.

Here’s three different ways for three different domains:

If learning an academic subject, the learning space is going to be papers, books and courses, linked via citations. Here are a few strategies helpful for efficient exploration:

1. Start with a course or textbook. Designed for learners, these will provide an entry-point that doesn’t always presume prior expertise.
2. Move to literature reviews and meta-analyses. For more specific topics, courses might not exist. Reviews and meta-analysis combine many different studies into one, so they can overview a literature before you dig deeper.
3. Follow citation trails. After these surveys, follow citations, centering on papers that come up again and again. Heavy citations show a paper is thought by other experts to be more important or foundational than others.

Even a narrow problem can often have tens of thousands of papers. A well thought out search strategy makes all the difference between understanding a field and being baffled by it.

Most languages have tens of thousands of unique words. Including proper nouns, expressions and other linguistic tid-bits, there would be a need for hundreds of thousands of memorized factoids for native-level fluency.

The order that these words are learned makes a big difference in functional abilities. Here’s how to optimize the path:

1. Master a few basic phrases to get started. This can be from any source: Pimsleur, Michel Thomas, textbooks or tutoring. This will give something to play around with.
2. Use the language in the setting that is most applicable. If that’s too difficult, pick an “easier” setting that is still close. Real conversations can be substituted with mock discussions using a dictionary. Real books substituted with graded readers.
3. Pay attention to any words that come up. Make flashcards to memorize any words that are encountered in the close-to-real situation.
4. Supplement these with a frequency list. Frequency lists often focus on small grammatical words, but knowing the translation to the most common 1000 English words is a good benchmark to be able to hold interesting conversations.

If we’re learning to do or make something, a project can help guide us. This works for programming, business, art and more:

1. Pick something concrete to make. If it turns out that it's too hard to make yet, start with a toy project that’s smaller.
2. Learn anything that is needed to build it. This is only a rough understanding, not mastery.
3. Put topics that come up on a “To-Learn” list. Any time a topic or subject comes up again—bump it to the top.
4. Learn the list. Pick the first item and set aside a fixed chunk of time to dig deeper. Then move onto the second item. If an idea previously covered needs more depth, add it back to the bottom.

The combination of a project with a list prioritizes what to learn. The project makes sure what we learn stays practical. The list prioritizes everything else and the fixed chunks of time keep us from getting derailed.