Eat lots of healthy foods. And read books!

Watch less porn.

Stay off of anything with a screen.

Tale time each day to be undistracted. Time to think.

Jot down questions during the day that make you wonder about stuff. Then, when you are undistracted, think about these questions.

Drink red wine.

Einstein said, I have no special talent. I am only passionately curious.

We can question whether he had no special talent, but passionate curiosity is a requirement for great thinking. What grabs your attention? What are you willing to devote your precious time to thinking about?

Read up on Great Thinkers biographies and their habits.
Read, read, read on a vast number of topics that you are not used to viewing.
Expand your mind by reading, travelling, talking with many different ideas,customs etc
Get out and explore.

Setting out with the goal of being a great thinker is probably the wrong way to go about it. I would shoot for a broad background in study and reading in the liberal arts and a knowledge of science. Try to get lists of classical and contemporary great books, read them, possibly with others and ask questions of them. Read different opinions on sociological or scientific concepts and form the habit of critical thinking. (Hint: there are databases in the library like “Point of View” that will juxtapose different sources.) If you are still in college, ask meaningful questions of the professors that impress you and talk to them during office hours.

But mainly – follow your intellectual bliss and see where it leads you. Have fun learning. By the way, that leads me to the man who first said “Follow you bliss, ” Joseph Campbell. He is the leading scholar on the interconnectivity of world wide mythology and if you wnat to see a great thinker at work, either read his books or watch the series Bill Moyers made of interviews with him. That man is a great thinker! Full disclosure: he was a Prof at my college and I’ve heard him lecture and also interviewed for the last seminar he was teaching.

I suspect the great fundamental requirement is wide ranging curiosity.

Know that you are a great thinker then say something.

Learn by doing and follow your interests.

Imagineer, ideation, act as if, believe, be that great thinker, and study up a bit before hand.

Get a job.

Start by being a moderately competent thinker and work your way up.

Read. Read excellent things. Read well and think about what you read. Keep a reading journal. Find out what’s already been thought.

Study logic and philosophy and learn how to think. It doesn’t come naturally to most of us. Examples of that are all around us.

Ask questions. Ask good questions. Ask questions well. Ponder the answers. Recognize the excellent ones. Learn to discriminate.

Consider abstractions. What is excellence?

Study the natural world. A lot of the answers are there.

And even at that, you’ll be a great thinker only if others think you are, and you might have to be dead a long time first. Self-esteem doesn’t count for much in philosophy.