It helps to have some familiarity with the literature, but with the resources of the internet at your fingertips, you can often construct a useful, well-supported answer even if you aren't already an expert on the subject.I think the important distinction is that it's not enough to "think" you understand the question, and have the right answer, you need to be able to demonstrate you do by finding sources that back you up. Starting out knowing which canonical philosophers have similar viewpoints to your own is helpful --people find it more useful to read Descartes expressing your opinion than userRandomNumber expressing it. I've had subjects, however, --epiphenomenalism, for instance --that I've learned about entirely from researching answers to questions about them.
I typically use a three paragraph approach myself. A useful pattern I often follow is first paragraph, direct, canonical, citation-supported answer to the central question as asked. Second paragraph, canonical answer to the question you think should have been asked. Third paragraph, your own opinion, clearly expressed as such, as a kind of editorial addendum to your answer. That way you can present your own views while still keeping the focus on the canonical answer to the question as asked. I've even seen answers go from downvoted to upvoted just by reversing the order to lead with facts and finish with opinion, rather than the other way around.
I've definitely had cases where I've gone out on a limb that I feel very confident about and then had to retract or change. One thing I do that I think too few users do is to edit extensively to respond to comments and concerns. That way an answer that starts weak can end up strong.