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How to find the right questions that I can answer?
I have favourited some tags. I see on homepage related questions getting updated regularly. But out of those questions I can find few questions that I can answer and add value. What is bad is most of those questions have already been answered or have vague answer such that I can't really figure out if that answer is what user wanted or not. Sometimes that is what user wants and I avoid adding another answer. On other questions I feel why should I spend some effort when someone else might be already composing an answer to the question.
How do you solve this kind of bystander effect. How do I find questions to answer matching my expertise? BTW I have fair amount of ROR, Javascript and relevant experience so I am not really a newbie.