
Respect other people's money as if it were your own money. Yes, this rule even applies to people working for big corporations. Always ask yourself if you would do the same if it was your own money.
Respect your own money and try not to waste electricity, water, paper, etc. Be also aware of all the very valuable free information that you can find on the Internet and thus avoid unnecessary lawyer, therapists and other professionals' costs. You can also easily compare the price of commodities to be sure that you do not overpay a product or a service.
Start with a Google search before you pay anything to anybody.