Musing has a team of curators that hunt through for great questions and answers and reward them with the Musing upvote. You can find the rules that they follow here:

https://docs.google.com/document/d/1WKYGhdPhLKNHytsxAPPQiXyv5UBY6nUKM8IhG5PUgfA/edit

This section is extracted from the above document. It covers "What makes a good quality answer:

• Good quality answers grab the attention of the reader without being spammy or click-baity
• Answer the question that has been asked. Refrain from going off on a tangent unless it provides clarity or an example supporting the answer. 
• Provide insight and support to opinion based questions 
• Formatting should be neat and help guide the reader through the answer
• Quality answers do not have a minimum length, but providing insight and elaboration to a “yes/no” answer can be much more helpful.
• Be original!"

You can also look through the "hot" answers to get examples of which answers are receiving upvotes. But as the last point above suggests, it's always good to bring your own style and personality to the table to get that authentic originality feel!