"Old" Financial Maxims?

[CubsFan23]

I was talking with an older colleague recently who said she was taught in school to never spend more than 1% of the cost of a house for the monthly payment (ie. 1% of a $200,000 house = $2,000 per month payment).

Along the same lines, she was taught to never spend more than 1 weeks salary on housing per month (ie. if you make $8,000/month, you'd pay $2,000 toward housing).

This seems like pretty sound advice; so my question is: Does anyone know of other "old" financial maxims such as these that people either 1) don't remember or 2) consider out of date or not with the times.

I wonder if we might be able to compile a list and then compare our situations to see if they fall in line with what used to be common sense.

Thanks!

[jeffrey]

Not really a maxim, but...

"A penny saved is a penny earned" - when you take into account taxes, the cost of the job (clothing, commute, etc) a penny saved is really closer to 2 pennies earned

[terry1156]

People at one point were supposed to put a 20% down payment down when buying a house, but I don't think anyone does that anymore

[disneysteve]

terry beat me to it.

Put down at least 20% when buying a house.
Housing costs should be no more than 28% of income.
Total debt, including housing, shouldn't exceed 36% of income.
Never finance a car for more than 3 years.
Save at least 10% of your annual income (gross) for retirement.
Pay credit card bills in full every month. Never carry a balance.

[jIM_Ohio]

pay yourself first
spend less than you earn