In your 30s or 40s? What you need to know about managing money.

Changing your financial state requires a kind of time travel to commune with your future self.  Where do you want to be in 10, 20 years? Are you on the right path, or heading in the wrong direction?

The time value of money—that is, how savings, investments and debt levels compound with the passing of years—means that money habits, good or bad, created when we start to earn cash echo into the decades that follow. And a whispered bit of wisdom up front can keep you from howling over your mistakes later in life.

We polled our NerdWallet network of Ask an Advisor certified financial planners about the greatest regrets and lessons you should learn in your 30s and 40s. Taken together, these could be considered 12 steps toward securing your financial future. And they all hinge on two keys skills we must learn—and often relearn—in our money lives: prepare and stick to a budget, and establish good savings habits.

Your 30s

Regret is a great fulcrum for change. By the time you reach your 30s, your attitudes toward cash (hopefully) have matured, tempered by past mistakes and informed by new responsibilities.

“People in their 30s are approaching that time in their life where they will have many life milestones: marriage, children and a new home,” says Jeremy S. Office, principal of Maclendon Wealth Management in Delray Beach, Florida. “By this time, you should have paid down (or paid off) student debts, settled into your career, and are probably thinking about starting a family. Hopefully the financial habits you set in your 20s will provide you with the knowledge of what you can save and afford to do.”

Still, the lure of easy credit that an established career brings can set up pitfalls, especially if you judge yourself against more-well-heeled friends and family. “Perception is not necessarily reality. Nice clothes, expensive cars and homes are not what they are cracked up to be, and are more of a liability than an asset,” says Anika Hedstrom, senior financial analyst and advisor for SkyOak Financial in Medford, Oregon.

“Avoid the ‘gotta’s—I gotta have this, I gotta have that, I gotta have it now,” adds Michael Keeler, president of GFS & Association in Las Vegas. “Credit is easy to get and easy to abuse. Live within your means.”

Tying the financial knot

The bigger problem in marriages is not incompatibility or infidelity, but rather mismatched ideas about money. Know your partner’s money personality and find the middle ground—fast.

The good news: A recent study found that millennials are better at having “the money talk” than older couples.

“Discover your partner’s money personality before you get married, and go through counseling if necessary. This alone can help minimize arguments of money, establish mutual expectations for using your money and create a shared vision or purpose for the future,” William Pitney, a financial advisor with Focus YOU in Foster City, California, says. “Once married, have a monthly big-picture review of your finances so you can monitor your progress toward your goals and make adjustments as necessary.”

Childproof your finances

There’s no greater joy than having a child—and no greater challenge to your finances. “Child care expenses alone could add over $10,000 a year on average to your expenses for the first few years,” says Shannon L. McLay of Next-Gen Financial.

If budgeting and savings haven’t been a part of your life, having a kid will kick-start that habit (and leave you kicking yourself for not starting sooner). Child care is costly, and college bills are not so far away.

“If not by now, the habit of saving can be expanded to include other priorities you may have,” Larry R. Frank Sr. of Better Financial Education says. “That emergency fund from your 20s? Keep it full, too.”

Rent or buy?

The largest purchase most people make is of a home. Although down payments may vary, advisors suggest having at least 20 percent  saved for a down payment to determine “how much home” you can afford.

But should you buy? The lure of building equity versus the expediency of renting comes down to one thing, really: How long do you think you’ll stay put?

“If your job has you moving or changing income a lot, best rent,” Frank says. “Buying high and selling before you can profit is how you lose your shirt.”

If you do decide to buy, “negotiate hard to get a great mortgage,” says Bonnie Sewell, a certified financial planner based in Leesburg, Virginia. If your career has you moving before you planned, “you could keep [the house] and rent [it] out, creating an investment asset.” But that can be a slippery slope if you’re not prepared for the added responsibilities of managing two homes in two locations.

Compound interest—the eighth wonder of the world

Be it your 401(k) retirement account, 529 accounts for your child’s education, life insurance or other investments, compound interest is a magical thing. This is the time to sprinkle that fairy dust in your financial life.

“As we all know, compounding is the eighth wonder of the world,” Seasholtz says. “Time and even a small amount of money adds up over the years; I still have my investment I began when I was 26 years old.”

“If your employer offers a retirement plan, participate, even if it just seems like a drop in the bucket,” Houchins-Witt adds. “The drops will eventually fill the bucket.”

Your 40s

If you were careless with your cash but didn’t have any regrets before, you certainly do now. That’s OK.

“Life happens,” Pitney says.

Don’t go into greater debt as a way to jumpstart investing. “For 40s, realize that debt service depletes usable money in a family’s after-tax, lifetime income pool,” says J Kevin Stophel, principal at KumQuat Wealth in Chattanooga, Tennessee. “Don’t think investments will necessarily outperform debt service, particularly unsecured credit.”

“Realize that the science of happiness informs us that it isn’t about things but is about relationships and experiences,” he adds. “Focus on these instead of bigger, better, more.”

Breaking up is hard to do

As about half of marriages end in divorce, it’s important to protect your financial independence. Some couples are able to amicably separate their assets, agree on alimony and leave each person’s credit rating in tact. For others, that is easier said than done.

“Divorce is not fun. Its not going to be an easy thing, so don’t kid yourself,” Hedstrom says. “It can get nasty. Protect yourself, use experts and make sure you always maintain your independence.” This includes knowing all of your and your spouse’s outstanding debts, account balances, and bills and due dates.

Ultimately, Sewell advises, “both spouses should understand the money!”

Ramp up your retirement accounts

Put your 401(k) into overdrive. If you aren’t already doing full employer contributions, do it. It might also be time to tip the savings balance from your kid’s education to your retirement. Your kids can get low-interest loans for college; there’s no low-interest loan for retirement.

“If you are behind on your retirement planning because of your [own] student loans, then your 40s are the perfect time to kick-start the retirement plan rather than boosting the education fund [for your child],” McLay says. Adds Houchins-Witt: “As your income increases, increase your retirement savings. You won’t notice it as much if you increase your contributions each time you get a raise.”

And continue to build upon the foundation you set in your 20s. “That emergency fund? Keep it still—you’ll have to have that until you retire—and yup, it will become the first dollars you can spend once you retire,” Frank says. “Retirement sounds like a long ways away, right? Graduating high school or college was just yesterday, wasn’t it?! In the blink of an eye, here’s the grandkids!”

Insurance matters

Now that you have people counting on you, it’s time to plan for the worst. Life insurance matters.

There are two major types: term life insurance, which covers a specific length of time (say, 10 or 20 years), and permanent (or whole) life insurance, which continues for as long as you live. Premiums for term policies are cheaper because the insurance lasts only a limited time, whereas those for permanent policies are more expensive largely because they provide guaranteed cash value for your beneficiaries.

“Term insurance is pure insurance, while permanent insurance is part insurance and part investment (with many moving parts, and a much higher cost),” says Jarrett Topel, owner of Topel & DiStasi Wealth Management in Berkley, California. “Term life insurance is like renting, and permanent life insurance is like owning. And, while we would all love to be owners versus renters, until you have significant assets and incomes, renting often makes the most sense.”

Len Cohen, owner of CF Services Group in Gaithersburg, Maryland, notes: “Some term insurance policies are convertible. This means that they can be exchanged for permanent policies during the initial term period in the same underwriting class, with no medical questions. Since you cannot be certain that your health will still be good in 10 or 20 years when you are more financially solvent, this is a very important feature.”

It’s not too late

So maybe you’re deep in credit card debt, you have no life insurance and saving for retirement feels like a fantasy. Here’s the thing: You still have two or three decades of working life ahead. It’s never too late to start.

“Meeting with a professional planner is perhaps the most important thing you can do to begin preparing yourself for life’s largest expenses: 20 to 30 years or more of retirement and paying for a college education,” Pitney says. “Many life events seem to derail plans, but minor changes in your 40s can have significant payoffs down the road.”