Image: Money jar © Big Cheese Photo, PictureQuest

Life moves fast. You think you have all the time in the world -- then suddenly your 20s are over and you're, like, a real adult.

Welcome to your 30s. The past decade was all about life's changes and getting to know yourself and your finances. You know the basics of money management. Now it's time to build on that foundation and secure your financial future.

Here are 10 principles that should be carved in stone for every 30-something:

1. Pay off your non-mortgage debt. Your 30s bring financial responsibilities you may not have had in your 20s, such as a mortgage or family. Nothing frees up cash to meet those obligations like getting rid of your debt. We hope you paid off your credit cards in your 20s. If you didn't, make it a priority. Next, focus on getting rid of student loans and other non-mortgage debt, such as auto loans.

2. Kick the debt cycle altogether. What good is paying off your loans if you take out another one and rack up new debt? An easy way to save for big-ticket items -- and avoid going back into debt -- is to put the money you would have used for monthly debt payments and interest charges into a savings account. For instance, after you make that final $300-a-month student-loan payment, keep making an equal payment to yourself. After one year, you'll have $3,600 saved.

3. Get serious about retirement. Your 20s were the time to start investing. No matter how little money you had to spare, it gave you a great head start. Now it's time to look at your goals and set a plan in motion to reach them.

Basically, you need to figure out when you want to retire, how much money you want to have by then and how much money you'll need to sock away now to reach that goal. Time is still on your side -- use it! Get serious now so you can have a comfortable retirement without sacrificing too much in the meantime. If you wait until your 40s or 50s, saving could become downright painful.

Don't be tempted to save for your kids' college expenses instead of saving for retirement. Make sure your own plans are on track first. After all, there are loans to pay for college, but not for retirement.

4. Diversify your investments. You want to make sure your money is spread among different types of investments so you're protected if one sector of the market tanks.

Generally, you should aim to allocate 50% to 55% of your portfolio to large companies, evenly split between growth and value; 20% to 25% to small companies, evenly split between growth and value; and 25% to foreign companies. (Check out Kiplinger's Mutual Fund Finder to zero in on investments in each category that meet your performance criteria.)

5. Continue to learn. Don't stop investing in yourself once you land a job. "Keep your earning power growing through continuous education, training and personal development," advises Knight Kiplinger, the editor-in-chief of Kiplinger.com.

6. Protect your assets. Even the best-laid financial plans can be derailed by an unexpected cost. So it pays to be prepared for the "what ifs" in life. For most 30-somethings, that means having adequate homeowners (or renters) insurance, health insurance and disability insurance.

It also means having an ample emergency fund. You started stocking your fund in your 20s, but by your 30s, you should have the full stash of money to cover three to six months' worth of expenses in case of a job loss, medical emergency or other surprise. (If that seems impossible right now, start with $500.)

7. Live simply. Deferred gratification may not be fun, but adopting a simple lifestyle is one of the surest ways to meet today's needs and still reach your long-term goals. Take a look at your spending to identify areas you could trim the fat. Small sacrifices can add up to big rewards.

It's easy to get jealous of friends and family who are living larger and seem to be doing much better than you are. Remember that keeping up with the Joneses is a losing game. Someone else's success may be a facade. Tune out the financial peer pressure around you and focus solely on what you know for certain: the state of your own personal finances.

8. Make your will known. A will ensures that your wishes are carried out should the unthinkable happen. Many assume that wills are for people who are old, rich, married or have kids. But all adults need a will to spell out their wishes in case they die or can't make medical decisions for themselves.

If you have children, make sure your will designates a guardian to care for them should something happen to both you and their other parent.

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9. Get a life . . . insurance policy. If you have children (or someone else who depends on you financially), life insurance is a must. If you were to die, you'll want to make sure they're secure. When you're in your 30s, you can get a great deal on term life insurance, buying a policy that lasts for a certain amount of time -- say, until the kids are grown.

10. Be charitable. As you become more established in life and in your finances, take the opportunity to give something back. Being charitable and socially conscious can be rewarding -- not to mention financially smart, considering the tax write-offs you get if you itemize on your returns.

If the new responsibilities of your 30s have you feeling strapped, give of yourself, not of your wallet. Volunteer your time or talents for a cause you believe in. It doesn't cost a lot to make a difference.