A good post is subjective, it can be a large wall of text or it can be a short statement. The point being is that you should know what you're talking about and you have the capacity to convey it in such manner that it's not boring to read if long but gets the point across if short.

I wouldn't say that this forum is hostile to newbies, a lot of the old users here are just tired of dealing with spammers and other entities that don't really want to contribute to the forum hence they may seem like unapproachable. If you really want to learn about bitcoin, you wouldn't mind their attitude and just try to learn something, real recognizes real as the saying goes.