Paragraph structure.

[J Riff]

Note the fine paragraphical structuring of the above rant. It's subliminal, the idea being to get the sense across, hence an expository approach makes the most sense - if you wish to convey something sensible, that is.
I still use high school and college manuals, which are full of exercises and lessons on constructing sentences, paragraphs and whatnot. There's various textbooks from the 50s in the warshroom here, and I blame them for any technical writing skill I may have acquired.

 

[nakins]

I don't know much about writing fiction, but in writing classes I had in school, I was told that a paragraph was the expression of a complete thought or idea that you wanted to convey, like describing a picture to someone.

 

[sknox]

Actually, that format stinks for academic writing as well. And it makes for boring presentations.

Say what you have to say. Period. If you have written badly, then re-stating it at the end will repair nothing. Chances are, your introduction will be as lousy as the body. The so-called hamburger format is for people who are afraid their point will be missed.

As for writing fantasy, I know of no guidelines at the level of paragraphing. For fiction more generally there are some conventions (e.g., a new speaker in dialog always begins with a new paragraph), but that's about it. My suggestion: just write your story. You'll buff up your paragraphs in the editing process.