There's a few things us regular users can do.
1) Use the site! Activity will make others want to use the website as well, so answer some questions, or even ask some yourself.
2) Tell your friends about it.
3) Upvote people who ask or answer questions, which will incentivize them to keep using musing.io.
4) Delegate SP to musing.io so they can reward the users more.
There are probably a few more things, but these are a good start if you want the website to grow.