Recently I started a Facebook page and a blog for Amerysk, a 1978 conlang I discovered through my friend Oak (the ORIGINAL Oak). I thought I'd share the experience for those doing likewise for their own favorite conlangs. (Doing likewise=starting Facebook page, not hanging out with the Original Oak.)
The first thing I did after starting Amerysk - A Lost Language (Facebook page) is that I clicked the little thingy in the upper right side of the screen and selected to use Facebook as Amerysk - A Lost Language.
Then I started looking for pages to like as Amerysk. I picked out pages dedicated to other conlangs and auxlangs. I got a lot for Esperanto and Volapük, a couple from Interlingua and then searched 'conlang'. I got a couple of pages people put up for their conlangs who wisely put '(conlang)' as part of their page title.
I might have done likewise but for one reason. The creator of Amerysk was a follower of the Asatru (Odinist, Norse Pagan) religion --- as was Oak, who provided me with the original Amerysk booklet. I figured the Asatru community was a natural place to find those interested in Amerysk, and they probably wouldn't be familiar with the word 'conlang'--- though I did use that in the official description of the page.
I did a lot of 'liking' of Asatru and related pages as well. The reason is that when you are using Facebook as your page, anything you 'like' is credited to your page and not to your Facebook account. When you 'like' some lonely conlang page without thousands of previous 'likes', they will notice, perhaps visit your page.
In addition, you'll develop a Facebook feed for your page--- when you are using Facebook as your page--- that is targeted toward the kind of sites that might be interested in your page. You can comment on interesting posts (thoughtfully) and some other folks may get to know you.
You could also like pages that are not directly related to your conlang, but don't be spammy about it, and certainly don't pick hot-topic pages like those for celebrities. Perhaps a selected page or two for some topic you find of interest. (I may 'like' my favorite Doctor Who page--- it's a sci-fi television series--- since the folks that comment on that page seem the type to like 'lost languages' and the like.)
I should add that those Facebook pages that are based on Wikipedia articles are no good--- they don't make posts or anything, so there is no one there to notice that you liked them.
Another essential thing is to add your conlang blog to Networked Blogs. Once you do, you can add a syndication of your page to your Facebook page--- so your blog posts will all be published on your conlang's Facebook page. (You can also have it publish to your main Facebook page--- the one under your name.)
I hope this information will prove useful to other conlangers thinking of starting a Facebook page. Once you do, be sure and go to my Amerysk page and like it, and post a link to YOUR page on my wall so I can like you right back.