Of course you can just say something nice, like "great content" or whatever. But it's better to add a tip, a thought, or even a link to one of your own blog posts if it's appropriate. Some admins might consider this a bit spammy and take it down, but that's very unlikely if it's related to the Page content. But generally speaking, admins tend to appreciate quality, relevant links and will often like them, say thanks, or even like your Page themselves.
By doing this you might be getting a bit of traffic to your blog. You'll also get on the radar of other FB users who may well like your own Page.
Of course you can share articles and blog posts by others as well. That's still to your benefit, particularly if you do it consistently, since you'll get known as someone who shares good stuff. The upside is that it's a lot easier than writing something new every time.
But whether you share your own or others' content, try and keep it as relevant as possible to the Page's subject matter. If it's about Twitter, for example, then just share Twitter related stuff. Don't start including blog posts about, say, how to get more traffic to your blog. Doing something like that will look spammy.
You're basically doing this to get your own Page on the radar of people who you already know are interested in its subject matter. So having a really good descriptive name for it is really important. It will stand out amongst all the other contributions and you're sure to get some likes as a result.