The key philosophers I’d recommend reading about to get a kind of big picture overview of the whole of philosophy and its history would be Socrates, Aquinas, and Kant.

But it’s often better to read ABOUT them, in secondary sources, rather than trying to read those philosophers themselves. Although the Socratic dialogues are pretty easy so you may as well do those.

Branching out from there, the next key players would be Plato and Aristotle, then Descartes and Locke, then probably Hegel and Russell. Each of those pairs will give you kind of an overview of the main “sides” of philosophy in their respective eras.

In a way you're on the beach, the ocean before you, and you not a swimmer. What is reasonable for you to do in that situation? Get wet, paddle about, get knocked down by a wave, have fun, and stay within your limits, probably not deeper than your waist.

If you're careless on the beach you could drown, among a number of lesser unpleasant fates. Reading out of your depth in philosophy won't drown you, but it is almost certainly a waste of time, energy, and money (on books - beware this latter!).

Here's a start. Get into your mind a rough timeline, starting c. 500 BCE to 2000 CE. Put names on it. That's enough. It is sometimes argued, with some justice, that philosophy just is the history of philosophy. Having a rough time-line of names will help you locate ideas in that history as you become familiar with the ideas associated with the names. How many names? Start small; and don't worry, it will grow.

Next your library or used book sources. You're looking for readable(!) brief intros. or guides. They can be about the thinking of individual writers, or history of problems or questions. I recommend in this mix Kant's two prefaces (or intros.) to his Critique of Pure Reason, and maybe a few pages more. The Kant is eye-opening, the real deal, and not easy - but in the prefaces accessible.

The next stop is usually a few of Plato's dialogues. Maybe then Descartes. Resolve to read original texts if you can, over secondary literature. Use the secondary as an aid to understanding the primary. The secondary is sometimes excellent, but it is always, well, secondary, if not outright wrong in places.

Two books I have found very helpful:
An Essay on Metaphysics, R.G. Collingwood,
https://www.amazon.com/Essay-Metaphysics-R-G-Collingwood/dp/1614276153

A Commentary on Heidegger's Being and Time, Michael Gelvin
https://www.abebooks.com/Commentary-Heideggers-Being-Time-Michael-Gelven/30464535224/bd?cm_mmc=ggl-_-US_Shopp_Trade-_-used-_-naa&gclid=EAIaIQobChMIkuvV_JXh6gIVB4TICh0XlweWEAQYAiABEgL_kvD_BwE

What is the real hazard of random reading in philosophy if you're new to it? That you will read and think you understand when in fact you understand it not at all.

Ok great thank you. I was a little intimidated going back to the older philosophers, but I'll start browsing some of those on Amazon also.

Keep in mind that if you do want to read the original texts, a lot of the older philosophers can be read for free online, so no need to buy books of them unless you really want the paper on your shelf.

The Stanford Encyclopedia of Philosophy is also a surprisingly in-depth free online secondary source where you could learn a lot for free.

Ok thank you

Nietzsche's "On Truth and Lies in a Nonmoral Sense" and "On the Use and Abuse of History for Life" can be found online to read if they are not already included in Basic Writings and Portable Nietzsche, and are not terribly long.