How to address a general audience

Question

I would like to know: When you are writing to a general audience, to whomever may be reading your letter / book / article, do you use the tú form or the usted form? Does it depend on the formality of the situation?

Answer 1

It would generally be better to use the usted form, because you would not (I'm assuming) know who exactly your audience would be. So, it's better to be safe than sorry.