The only way to learn is to be tea-bagged by a Space Marine...
Seth's written some fairly great financial advice. It's easy to follow and guaranteed to work. There's only one problem: No one will listen. Well, no one who doesn't already know will listen. The problem is simple. Finance has a lot of momentum. You don't know that you're getting crushed until there's nothing you can do about it any more. It's like... global warming, I guess.
There's exactly one way to learn about good financial management: Play an RTS against someone who is good, or a skirmish against a good bot. Nothing will show you how much good resource management is at the beginning of a game until the twentieth odd game when you realise that someone wasting that 200 odd req. was what caused the tide of battle to turn. Eventually, you'll get the hang of getting a good build going. Eventually, you'll realise what you need to do to stop being overrun -- and it's all about resource management. Don't get me wrong, there's often a ton of good battle strategy there too. Knowing when to run away and rebuild your army in DoW is important. But without the economy, you're not going to win, because the other guy is seriously rolling in it, so he can spam his units against you, and you have to work really hard only to get pwned.
If you want to teach your kids about good financial planning, get em to play DoW.