Long before David Mendels became an advisor, he saw the importance of financial planning no matter what a person's age is.
He was in his 20s when a married couple he knew from college were killed in a private plane crash. While their death was devastating enough for loved ones, the agonizing part was that they had a 3-year-old daughter.
Each half of their extended family wanted to do the right thing by taking custody of the young girl. The situation had the potential for much ugliness among in-laws, until it was discovered the couple had created a will only days before their death. In it the wife's brother was named as their daughter's guardian. And at that point, because the young parents' wishes were clear, all arguing stopped.
"If you are parents of small children, I don't care if you don't have two nickels to rub together," said Mendels, a certified financial planner and director of planning at Creative Financial Concepts. "You have to have a will and name someone to be a guardian for your children. You have to take care of your kids," he explained.
Having a will is just one aspect of financial planning that depends on where you are in life. And, as illustrated above, financial planning is about more than investments and retirement savings.
While everyone's situation is different and their planning needs are not entirely age-specific, some generalizations can be made.
Financial planners say that for people in their 20s—when many people are just embarking on careers and are financially beholden to no one but themselves—several aspects of planning are important whether they have children or not.
For starters, experts advise building an emergency fund worth at least six months of your salary, thinking about saving for retirement and getting a handle on what you're earning versus what you can spend.
"What usually occurs with them is you're trying to teach them how to save money," said Mark LaSpisa, a CFP and president and managing advisor at Vermillion Financial Advisors.
He said part of his challenge is helping young clients determine their spending priorities.
"It's getting them to see that if they buy that big-screen TV, they won't be able to go on vacation," LaSpisa said. "Or if they want that really kick-ass car, they might not be able to buy a house for a while."
Advisors also encourage people to start saving for retirement as early as they can, especially to the extent they can take advantage of any matching employer contributions to their 401(k) plans.
Having long-term disability insurance is also important.
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"If you're disabled … you won't be much concerned about saving for retirement," said Harold Evensky, a CFP and chairman of Evensky & Katz/Foldes Financial. "You'll be thinking about how to deal with what you have."
According to the Council for Disability Awareness, about 1 in 4 of today's 20-year-olds will become disabled before retirement. And the average absence from work is 34.6 months.
If you end up being unable to work due to injury or serious illness, a disability policy typically provides you with a portion of your salary—anywhere from 50 percent to 80 percent—up to certain limits.
Also important is creating powers of attorney. This means giving someone the authority to handle your finances if you cannot, and choosing someone to make important health-care decisions if you are unable.
And yes, if you have children, make sure you have a will.
For people in their 30s, life can get a bit weird. Advisors often have to rein them in when it comes to spending.
"What's interesting with them is it often becomes about keeping up with the Joneses," said LaSpisa at Vermillion Financial Advisors.
This means spending money on things that have no value other than how others view you.
"I try to get people to make better decisions and highlight the consequences of their decisions," LaSpisa said. "It's things like buying a car they can't afford or buying a house in a neighborhood they can't afford."
LaSpisa said he points out that the purchases represent too much of their income and that spending the money on those things means they won't be able to meet other financial goals, like putting money toward retirement.
"When you lay that out, they start realizing it maybe wasn't a great idea," LaSpisa said.
Another life change that 30-somethings often face is having a spouse or partner, a house and kids. That brings new complications into their financial planning.
"Life insurance definitely comes into play if they are a traditional family or have kids," LaSpisa said.
At that point in life, term life insurance is worth considering. The policy amount you get depends on how much your survivors would need to replace your income for things like a mortgage, your debt and child care.
When people are in their 40s, new concerns come into play. Their kids might be getting close to adulthood, which means college tuition might be on the horizon.
By this point, it's wise to have started thinking about how to pay for kids' college, whether through a 529 college savings plan or other means. And advisors emphasize that it's more important to save for your own retirement than your children's college expenses, because financial aid is available for college but not for retirement.
Your 40s are also the time to start thinking about getting long-term care insurance for your retirement years. In simple terms, it provides coverage for the cost of care for people with a medical condition that requires supervision, whether in a nursing home or elsewhere.
"If you don't do it in your 40s, definitely consider it in your 50s," LaSpisa said. "After that, it can get cost-prohibitive."
People in their 50s are in the home stretch of retirement planning. If they have not tended to all of the things they should have at a younger age, now is the time to do it.
And as far as retirement savings go and how to divvy up your assets, it's all about risk tolerance and time horizon. Advisors are loathe to say a 25-year-old should have more exposure to stocks than a person on the verge of retirement, because it really depends on to what extent a client can stomach the volatility of the market.
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But what all planners agree on is the benefits of financial planning, regardless of your age.
"I'm passionate about the process of financial planning," said Evensky of Evensky & Katz/Foldes Financial. "People need to go through it."
He added, "Everyone's future will depend on their insurance and their money saved. And to do it [without planning] is a dangerous way to live your life."
—By Sarah O'Brien, special to CNBC.com