How formal should I be?

Well, I run a Japanese-language Facebook page about a favourite actor.
My Japanese is pretty good, but there's one thing that I've been wondering: how formal should the Japanese I'm using on this page be?

Considering that some fans really have/show respect for actors/actresses, and you don't know each other in person, I would start off with "-desu/masu" polite speech, and see how people make comments on your page - you can respond in similar tone (or as the host of the page, a bit more polite than others).

If you already have a page up and running, you could maybe post a sample sentence here, just so that we can see what kind of tone you are using?

saju,

I'm sure there are loads of similar Japanese-language Facebook fan pages you can refer to. Study them well and see how the webmasters react.

Generally speaking, I think most people communicate by teineigo (〜さんは、…してるんですね), unless you know each other really well especially in the physical world. But more importantly, you may want to keep your comments short yet sincere, so that things don't get out of hand. You can also be humorous or sarcastic about users who visit your page often, but still using keigo is the key to maintain a friendly atmosphere.

Thank you really a lot for your help.
It cleared things up and I appreciate it!