Use your brain. Train your brain to discern good and bad, right and wrong.
Don't believe everything you hear. Actually, make your own informed decision before grabbing hold of some belief or "fact."
There are all sorts of things told us in the public arena that are motivated by greed.
Beware. God has given you a brain so you would use it. Use it. Don't be caught off guard.
Getting into the Word of God for yourself, letting it teach you is one of the best (maybe the best) ways to train your brain to think.