An excellent post by D.K. giving wise advice. I especially like the parts which advocate making things as professional-looking as possible: a formal supplementary rulebook (item 4), custom player cards (item 5) and precisely-matched map stickers (item 5), all produced to a high standard of quality. D.K. also makes good points about having the house rules appear credible rather than arbitrary (items 3, 6 and 7). And item 10 underlines that it’s important for house rule designers to decide to what extent they want to balance creating rules with a high personal appeal to themselves versus creating rules which have broad acceptability to the A&A community; the two approaches aren’t necessarily mutually exclusive, but designers need to consider which way they will tip on a particular house rule proposal if they have to choose between personal appeal and broad acceptability.
Here are a couple of other ideas, to which I’ll give numbers that continue D.K.'s 10-item list:
11. Keep the number of house rules manageable. House rules can be viewed as seasoning which should be applied sparingly to the game; their purpose is to tweak the official rules, not replace them. The greater the number of house rules, the harder they are to memorize and the more they have the potential to fundamentally alter or unbalance the game. One way of splitting the difference is to have a large list of potential house rules, but to use only a small number of them in each game; choosing with your fellow players which house rules will be used in a particular game can be fun, and it adds variety to your get-togethers because you’re playing a slightly different game each time.
12. Have your supplementary rulebook state the overall objective of your house rules (assuming that they’re guided by a defining principle). For example, the purpose of your house rules could be: a) to make the game go faster; b) to alter the balance of victory probability for one side or the other; c) to explore a particular alternate-history scenario; d) to correct perceived flaws in the official rules; e) to reflect more accurately the performance and/or cost of particular combat units; f) to create a game variant that uses a fundamentally different game mechanic (such as concealed play, using two game boards and a referee). Players may be more willing – or may even be enthusiastic – about using your house rules if they understand what you’re trying to accomplish with them.