Philosophy is a science different to those empirial ones like physics or biology, but also literature, and it is different to non-scientifial sciences like religion or arts, though there are several crossovers. To study philosophy we need patience and a different kind of thinking which we can only learn by practicing. If we learn this different kind of thinking, philosophers believe, that we can gain a knowlegde that will help us understand how the world works. There are many questions that can probably only be answered by philosophizing or believing (which would be a part of being religious).
Now there were many famous philosophers in history. To name some of them: The ancient world had Sokrates, Aristoteles, Platon, Seneca, Epikur or Cicero. In the middle ages there was for example Thomas of Aquin. Then came Descartes, Hobbes, Habermas, Mill, Kant, Heidegger, Locke, Nietzsche, Freud and many more. Names we all know and people who have changed the world with what they said.
They all had different theories and ways of practicing their philosophy, but all of them were important and probably all of them said something that is true. They made it obvious that philosophy is not a science about one thing that is important, but many different things. They explained to us their theories about luck and truth, about right and wrong, about how we should behave and why are some things better than others. Because of them we now have different categories of philosophy: A theoretical one about ontology and experiences, then a practical one that asks how we should live and how a state should work and many other categories.
To philosophize we have to think clearly, we have to differ arguments and analyze them properly. And we have to distinguish ideals and reality.
Of course there are many doubts about philosophy: Why on earth should we think about such things, when we never can be sure about the answer? Though I think this science may help us understand a lot more that is going on in the world and to learn a different way of living. As some philosophers say: Living philosophy is the only way to become a really happy and lucky human that is satisfied with what he has.