I use the internet to put in practice what I am learning about critical thinking and argumentation (critical thinking course on Khan Academy).
I understand that meatspace doesn't frequently offers opportunities to test skills like that, but when looking for those opportunities online you should be very picky on where to look. Avoid newspaper sites and (most) blog comments. You need to find environments in which disagreement is a way to find the truth and where changing your mind is encouraged. These are pretty rare. Although if you want to practice argumentation, you might want to check out /r/changemyview on reddit
Especially in the comments of political articles or about economic issues I find myself arguing with people who question my authority about a topic rather than refute my arguments.
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Examples may be:
1:
Me: I think money printing by the Fed will cause inflation if they continue like this.
Random commenter: Are you an economist?
Me: I am not, but it's not relevant.
Random commenter: Ok, so you are clueless.
2:
Me: The current strategy to fight terror is not working because ISIS is growing.
Random commenter: What would you do to stop terrorism?
Me: I have an idea of what I would do, but it's not relevant because I'm not an expert, but do you think the current strategy is working?
Random commenter: So you don't know what you are talking about.
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It is not about my opinions above, or even if I am right or not, I would gladly change my opinion after a debate, but I think that I am being disqualified unfairly.
If I am right, how should I answer or continue these conversations?