I just worked out I registered my first domain name in 1996. So I have quickly recalled the years of joy I've had registering domain names!
Rules pre 2000 to create a Domain name portfolio - Register 100's of business names for every domain name. (e.g. "Greater Interactive Research Laboratory" was the business name I registerd to register a domain name. Of course it was related to my Software Development company. I used the "G I R L" letters to meet Domain Name registration requirements back then to register Girl.com.au. (We actually built this and sold the business later on to the guys @ Trellian)
Rules mid 2000's - register anything and everything and hope Auda don't come after you. (well that didn't work....)
Rules today - just follow the rules. It's not has hard as it use to be. Ignorance is no defence.