Ink-Berry, the minimum to write is one paragraph, but I'd prefer more, especially in the beginnings considering the beginning posts are usually longer anyway. There should be no 'one-liners', and your grammar and sentence structure must be at least a little above understandable, such as using correct punctuation and capitalization. As far as "size of posts" goes and how I define a paragraph, as Casual Role-players you should know when you've got at least enough for a passable post. For example, the bare minimum of text I will accept in a post is as long as this post is. However, whether you define your paragraphs by word-count or sentence-count, the main things you should consider when wondering if a post is long enough are "does this contain all the necessary information for my response," and "have I responded to everything I needed to respond to."