Intelligence is general knowledge plus critical thinking. We can all have that. General knowledge comes from reading and hearing a lot of new ideas. Fortunately for you, suffusing the very atmosphere around you right now is the greatest library ever assembled. Read it. Critical thinking is just practice at asking yourself why. Why do you believe what you do and why do you reject the things you reject? If your answer is ever "because I read it here", "because that guy told me so" or "because that's what everyone believes", you need to go deeper. Really think about what makes up your core assumptions. Picture the world from someone else's point of view, with different assumptions for a while.
Mokalus of Borg
PS - In short, practice thinking.
PPS - Somebody has to.