Make posts on the page. Share posts from page into any groups that are relevant to your niche. This funnels people in like crazy.
As jul3s said above, though, page reach is dead. You will want to have a pinned post at the top of your page funneling people somewhere else (site where you capture emails, insta, YouTube, a fbook group you started, etc).
Most niches have dozen of relevant groups you can post in.