(This post is based on the article of the same name from the official wiki.)
Have you ever browsed the #NJSLYR tag, saw the NinSatsu writing style that the 'heads use, and thought something like "I want to write like this!" or "Tatsujin!"?
This page is filled with instructions for such newbie-heads.
(Even though he's acting all high and mighty, the author of this page is a newbie, too. Sugoi-experienced 'heads, do feel free to edit it!)