How can one become successful in musing.io? people's are not getting their upvotes?what is their fault?what is their mistakes?what kinds of answers do musing expect?
Being respectful of others. This includes being respectful of other people's work and not plagiarizing.
If you had to look something up on-line to help you answer a question then cite the source. Nobody knows everything so there is no point in pretending like you do know everything.
Some answers require a lot of explanation while others require very little. My experience is that questions that require more detailed answers tend to do better with upvotes on musing.io. This makes sense since a complicated question can require more work to answer. When it's broad enough you might also make a list to answer a question.
If you are answering a question with a paragraph or two you might as well take advantage of the "post to blog" option. Even if an answer you spent ten minutes typing out doesn't get an upvote on musing.io, it might on steemit.
Add tags. If you post a response to a question on both musing.io and steemit you can add additional tags to the steemit posting by editing it. If someone just tagged "nature" for their question but it also would fall under "science": and "education" then add those tags to your steemit post after selecting the "post to blog" option.
Just have fun. Sometimes you get an upvote and sometimes you don't. That's the way it is so focus on what interests you.