"The measure of a life is not its duration, after all, but its donation."  Corrie ten Boom

Eighty-nine percent of Americans donate money to churches and charities. Americans gave an average of $1,620 each in 2008, the most recent figures available, according to the National Philanthropic Trust, and even that is 2% less money than they donated in 2007.

If you ever doubt humankind’s generosity, consider that more than $644 million has just recently been donated in the aftermath of the earth-shattering January 12 earthquake in Haiti—an unprecedented amount of money, according to the Chronicle of Philanthropy. The average amount of money per donor is less than was donated in the wake of the 2004 Indonesian tsunami, but there have been millions more people donating. The advent of donating money by texting from mobile devices has likely contributed to the number of donors—12 million donors chose this method—but clearly, there is something more at play than convenience.

The Bible’s Old Testament demands a “tithe,” literally, 10% of one’s income. The New Testament, however, is clear that Christians should give money to the church to further the gospel, but the emphasis in on a freewill gift without a specific formula for determining how much money should be given. Orthodox Jews follow the Old Testament law and donate 10% of income to charity.

Alms-giving is one the Five Pillars of Islam, and though the amount of money to be donated isn’t specified, Muslims must donate at least a small percentage of their surplus income to the poor, or risk that their prayers will no be heard.

The tradition of charitable giving is universal, and in many European countries, there are compulsory taxes for money to be given to churches and charities. There is no such tax in the United States, but the importance of charity is clear in our tax code that provides tax credits to donors.

Is charitable giving a moral obligation? Is it evidence of innate compassion? If it is a moral obligation, what is the “right” amount of money to give?

There are two schools of thought regarding how much we should give to help others. One is that we should give until it hurts; we should make a sacrifice. The other thinking is that we should give until it feels good, and when giving feels good, maybe that is evidence of our innate compassion.

The three largest purchases you’ll make in a lifetime are most likely your home, your education and your car. Before you start looking at any of these, you’ll have to ask yourself “How much can I borrow?” In each case, you’ll probably want to buy more than you can afford, so you’ll need these basic guidelines to bring you back down to earth.

These are, by the way, the same guidelines lenders follow, but they’ll also factor in your credit score and previous payment history. That means, while you’re asking yourself “How much can I borrow,” the lenders will be looking at how much you can afford to borrow.

How much can I borrow for a house?
The first place to start is with your down payment. The rule of thumb is that you should have a down payment equal to 10 to 20% of the home’s price. Since the median price of a new home is currently $204,000, you need to save roughly $30,000. Consider consolidating debt with a personal loan a year in advance.

To get the best deal on your mortgage, you need a good excellent credit score, and that mean your debt to income ratio (DTI) should less than 36% of your gross income. If your annual earnings match the median salary of $70,000 for a family of four, that means you should have no more than $25,200 in debt, not counting your housing costs.

Your monthly payment should be no more than 28% of your monthly gross income. Again, if you’re that Average Joe all our numbers are based on, your monthly payment—including principal, interest, taxes and insurance—should be no more than $1,633.

How much can I borrow for my education?
Your monthly payments should be no more than 10% of the projected monthly income of your first job out of college. For instance, the average student loan debt for an undergraduate education is $21,000. Paying 8% interest on those student loans for a 10-year term will cost $250 a month. If your first job out of college pays at least $30,000, you should be able to make the payments without too much trouble, IF you avoid amassing a lot of credit card debt while you’re in school.

How much can I borrow for a car?
When you’re asking yourself what you can afford, be sure to add in expenses like insurance, gas, maintenance and depreciation, which add a lot to the cost of car ownership. For instance, the manufacturer’s suggested retail price for a gas-sipping 2010 Toyota Prius is $22,400; add in those addition expenses and the real cost is $35,307. Before you buy, check out the True Cost to Own™ calculator at Edmunds.com. And remember, you can’t let your monthly car payment push you over that 36% DTI.

The decision making process for all purchases should always begin with “How much can I afford?” instead of “How much can I borrow?” By using these guidelines, you’ll know what to expect from your lender, and avoid getting in over your head if you run into an unscrupulous loan officer.

Just like a doctor can make a quick assessment of your general health by checking your blood pressure, heart rate and temperature, with just a few quick questions you can get an overview of your personal finance health.

• Housing costs: Your total monthly housing costs, including mortgage or rent, property taxes and insurance shouldn’t exceed 28% of your gross monthly income.
• Debt payments: Look at your monthly payments for housing, loans and credit card debt. You should be spending no more than 36% of your gross monthly income on these bills.
• Emergency savings: You should maintain an emergency account with a balance equal to three months of expenses. If your household includes children or is supported by only one income, double that.
• Investment portfolio: The younger you are, the more risk you can afford to take in the stock market. As you get closer to retirement age, your portfolio should be weighted more heavily toward bonds. Deduct your age from 120; that’s the percentage of your portfolio that should be invested in stocks.
• Company stock: Maintain a diversified stock portfolio. Take advantage of an opportunity to buy you employer’s stocks, but don’t go over 10% of your total stock portfolio.
• Life insurance: Multiply your annual salary by five to determine your life insurance needs. If you have several children or a lot of debt, double that. If, however, you have no young children or debts, you can do without entirely.
• Retirement savings: Apply these general rules of thumb: If your employer matches your 401(k) contributions, contribute the maximum amount. Take advantage of any tax-deferred retirement accounts you can. If you’re conflicted about whether to save more for retirement or for your child’s college education, choose retirement; there are no retirement scholarships.

There are no rock ribbed personal finance rules, but tending to these seven areas of personal finance will go a long way to ensuring your security and your family’s. For more information on retirement planning, consult with a personal finance advisor.