Since the subject of game rules writing, and written rules sets, has been floating around here in different forms, I'd like to start a thread dedicated to exploring what people here have discovered works very well in their own rules sets. I'm not talking about game mechanics, here, but what, in the actual written rules, have you found to be most effective?
Here are some of mine:
Glossary: One of the things I've done for years is standardize my rules writing as much as possible. One thing I always add is a glossary that defines the game terms used elsewhere. Each entry in the glossary has a page number that tells the reader where the term is first used in the game.
Pseudo-Hyperlinks: This is something I've just recently used, and thats to place terms to be defined or the names of rules that have examples attached in a different color. These refer to text boxes in the sidebars that share that color border around the textbox.
Visual Example Image Set: I always design a "play set" of game graphics as seperate computer files, and these are used to create the game's example pictures. Having these seperate from the "working" files leaves me free to move them around, as opposed to having them in printer- or cutter-friendly formats.
FAQ: I've only recently added one of these, but it helps me make rules points in a conversational way, elaborating on subtlties or strange situations that may come up, without harping on them or bringing up strange situations during the rules explanations. I'll likely add these into older rules sets, and continue with them in future games.
Notation: Since I design a lot of abstracts, I always like to offer a system of notation with my games. This makes e-mail play simple, and offers an immediate standard notation.
Example Game: I always include the notation for a complete game of every abstract I write. For board games, I always include at least one full round of play.
Puzzles: Think of the "knight's tour" for chess, and all the chess puzzles offered out there. I think that abstract games offer great puzzle opportunities, and I always include a few.
Yes, I use a FAQ to clarify, rather than actually explain the rules. There are some times where perfectly reasonable play will lead to situations that either are pretty strange, or even just look unusual, and lead players to ask "Did I just do that right? Is this possible?" FAQs are great for answering these questions, since they are about the implications of rules, rather than the rules themselves.