Speak your mind. Don’t be afraid to disagree, but know the difference between healthy disagreement/debate and an argument. Don’t call people names or lose your temper when debating. And as you’re stating your opinion, keep one thing in mind – you’re not that smart.
You won’t always be right and you shouldn’t always have an answer to everything. It’s ok to say, “I don’t know.”
Do not cling to an opinion and be afraid to change it – keep an open mind. If you gain more information on a subject, whether by collecting it yourself or being told new info from someone else, it should either be adding to your argument or breaking it down. Either way, the balance should be shifting one way or the other.