As a previous comment has already pointed out, it really depends on what kind of philosophy you want to look into. But ancient Greek philosophies are a good place to start, if you're interested in understanding Western Philosophy at least.

In my opinion, the funnest and easiest of Plato's dialogues is Symposium, which deals with some interesting ideas about love while also discussing some absurd ones. Of course, you also have Plato's Republic, however it may not be the easiest to break into. There are a tonne of other ancient Greek and Roman philosophers to look at, but many start with Plato.

If you wanted a book to help discover what concepts you might be interested in then may I recommend

50 Philosophy Ideas by Ben Dupré

and if you wanted a book just to get your mind thinking philosophically, then

Paradox by Jim Al Khalili.

Both are easy reads and give summaries of various concepts and problems. Once you've started your search, then maybe start looking for books or writers in that field. For example, if you were interested in learning about the development of Western philosophy, you may want to check out Bertrand Russell's History of Western Philosophy, though it can be quite dense.

Another way of easing into one kind of philosophy is through novels. Many authors integrate philosophical concepts into their writings e.g. The Stranger by Albert Camus or Dostoevsky's novels (again, often quite dense).

As others have already mentioned, there are a load of wonderful interesting areas of philosophy to explore but it really depends on your preference. Some people prefer more casual philosophy rather than jumping straight into Hegel, or some might enjoy pondering St Augustine's musings on the philosophy of time than Plato's of society and politics in the Republic. Hope this helps.