My advice whenever this comes up, is start with an historical approach, and specifically with the pre-Socratics, leading on to Plato. There's a vast amount of literature of course, but the historical perspective at the very least gives you way to organise your approach. The second would be, read thematically - follow the themes of the major schools and ideas, and see how they develop over time. Thesis and counter-thesis, conjecture and refutation. And finally, develop an appreciation for dialectic. The dialectic approach to a topic comprises a discussion between opposing theses, which discloses things available through the tension between these two theses, that are not disclosed by any single voice or proponent. That dialectical approach is typical of Plato's dialogues, but there are many more examples.

No doubt others will have plenty to add but that's my two cents.

Im only an enthusiast. What i do to guide my studies is to have a look at different universities curriculums and read first the most common names, down to the less common ones. About what the previous response said on reading thematically, i also try to follow one author's complete bibliography chronologically, since the understanding of one single book is frequently tied to the previous or developed better on the next.

Also, I would recommend something like this:

https://www.amazon.com/Philosophy-Made-Simple-Complete-Important/dp/0385425333#reader_0385425333

I have an earlier version I bought about 20 years ago...it's kind of a good synopsis covering the basic domain's. I still refer to it on occasion when I'm trying to KISS something :wink:

From a previous thread discussion on same topic.

To get a broad acquaintance with the history of the field and its range of thoughts, I think these are probably the most important authors to read:

Socrates (via Plato)
Plato
Aristotle
Aquinas
Descartes
Locke
Kant

I recommended these guys because in the history of philosophy, there is a tendency for there to be periods of two opposing camps or trends or schools, and then one philosopher or school of philosophy to unite them, and then two new opposing schools to branch off from that again, back and forth like that. These authors give an overview of those opposing schools, and the figures who united them and from whom new ones were formed, as illustrated here:



We don't have a lot of material from Thales, the other Ionians, or the Italiotes (collectively the Presocratics), and their work was really primitive and not super relevant today, so I skipped them entirely. Socrates is really where philosophy as we think of it begins, and his student Plato and Plato's student Aristotle were the founders of the two main opposing schools during the Classical period of philosophy. In the Medieval period things were largely reunited into one school, the Scholastics, of whom Thomas Aquinas is the preeminent figure. The Modern period began with Rene Descartes, the first of what would come to be called Rationalists, and their opposing school, the Empiricists, got their beginning with John Locke. Then Immanuel Kant once again reunited philosophy, until it split again into this Contemporary period's still-unreconciled divide between Analytic and Continental schools, who are too numerous and recent and ongoing to pick preeminent figures for. So that's why I recommend those authors for a historical overview.

Your school probably has courses on each of these guys, and you'll probably be required to take at least a few of them as part of your major. If you have time, two other Modern-era philosophers who I found very interesting and helped expand my worldview a lot are the empiricist George Berkeley and the rationalist Baruch Spinoza, who both have very unusual pictures of the world but ones I think have valuable ideas to contribute.

And then you should acquaint yourself with the foremost thinkers in the fields of:

Philosophy of Language
Philosophy of Art
Philosophy of Mathematics
Ontology / Metaphysics
Philosophy of Mind
Epistemology
Philosophy of Education
Philosophy of Religion
Metaethics
Philosophy of will
Ethics (especially utilitarians and deontologists)
Political philosophy
Existentialism / “philosophy of life”

Your school probably has a class on each of these too (except maybe the last), and you'll probably be required to take at least some of them anyway.

I think these give a thorough overview of the range of topics philosophy discusses, which all inevitably interrelate with each other. At the most abstract is philosophy of language, and two only slightly less abstract fields that are kind of opposite one another, philosophy of mathematics and philosophy of art. I missed all of those in my formal education and I regret it.

Instead I focused on the two halves of what I'd call core philosophical topics, roughly ontology and epistemology on one hand (about reality and knowledge), and ethics on the other hand (about morality and justice), which I would subdivide into fields analogous to ontology and epistemology (that are also roughly related to utilitarianism and deontology, hence why I emphasized those in particular) but that's not standard practice so I won't go into that here. Metaethics is an especially important part of ethics that ties in closely to philosophy of language, so I recommended that in particular.

Philosophy of mind ties in really closely with ontology and epistemology, and I think free will fits into a similar place regarding ethics because of the connection between free will and moral responsibility. Political philosophy has its obvious connections to ethics as well, being in essence the most important practical application of ethics, and though there doesn't seem to be a single established field that's perfectly analogous to it in relation to ontology and epistemology, I've found significant parallels in both philosophy of education and philosophy of religion, so I recommend those as well.

And lastly, the biggest thing that I overlooked in my formal philosophical education, opposite those abstract fields at the start, is the practical application of philosophy to how to live one's life meaningfully, which Continental schools like existentialism and absurdism address. This topic doesn't seem to have its own name, that I'm aware of, but I colloquially refer to it as "philosophy of life".

The bottom part of this illustration from my philosophy book illustrates the structure I think these fields have to each other:



For these purposes you can ignore everything above Metaphilosophy on that chart, as those are particular views of mine and not philosophical topics (this is actually a chart of the structure of my book, the latter part of which is structured after this same array of topics).

Speaking of which, add Metaphilosophy to my list of fields worth studying if you have room to squeeze it in. What even is philosophy, what is it trying to do, what constitutes progress at doing that, how can we do it, what does it take to do it, who should do it, and why does it even matter?

Bertrand Russell's History of Western Philosophy. As introductions go, it doesn't get better and if you ask philosophy professors which book they read that first got them properly interested in philosophy this is the one that is consistently mentioned more than any other.

I was also thinking of recommending that in addition to the rest.