For the narrow subset of technical questions, How to Ask Questions the Smart Way is useful.

But if you don't have a problem to begin with -- if your aim is "learn more in field X," it gets more complicated. Given that you don't know what questions are worth asking, the best question might be "where would I go to learn more about X" or "what learning material would you recommend on the subject of X?" Then in the process of following and learning from their pointer, generate questions to ask at a later date.

There may be an inherent contradiction between wanting nonspecific knowledge and getting useful, specific answers.