Big Jim over at 'Galaxy in Flames' recently posted an article on design philosophy that I feel made insightful conclusions on the best approach to rules design. It's definitely worth checking out:
"When starting out you need to have a clear vision of what you are trying to achieve, but you must be open to feedback and making the proper adjustments to the list. After all what is the point of creating a fan-dex if you are never going to get to use it?"
A clear purpose makes for clear, unambiguous rules. If you want a concise design with no superfluous wordplay make note of exactly what you want each unit to do and try to keep units specialized rather than general-purpose. This purpose may even change over time, but as Jim says, this will only make your rules more available to other players.
"First off designing an offshoot of an existing codex is the best route to get your 'feet wet' in the fan-dex realm. They tend to be the easiest projects to balance if you keep your goals reasonable."
Another good point I'd like to comment on: Using GW material and emulating their style wherever possible gives your rules that 'authentic' touch that you'll need if you're going to win over the hearts and minds of your peers.
What advice can you guys give to newbies looking to start their own projects?