For those in their 20s and 30s, virtual worlds such as MySpace, Facebook, and Second Life may well take priority over retirement planning. But putting off those plans could be a big mistake, according to Mark Bruno, who explains why in his new book, Save Now or Die Trying.

A writer for Crain's Pensions & Investments periodical, the 29-year-old author provides insights from a variety of retirement experts at top firms, including Ameriprise (NYSE:AMP), the 401(k) Association, and Hewitt Associates (NYSE:HEW).

Put time on your side
The premise of Bruno's book is quite simple: The earlier you start investing, the better.

That's hard to argue with. Unless you have a trust fund, marry a rich person, or become the next IPO billionaire, you'll probably need to get serious about investing for retirement. Pensions are fading away, and Social Security seems like a pipe dream. Even now, those Social Security payments are fairly meager.

But when it comes to long-term decision-making, avoid things can be easy. Aren't there more pressing matters to worry about now, such as buying a car or a house, or paying for education?

Well, sure. But the good news is that you don't have to invest much. For example, Bruno shows that a $4,000 annual investment -- starting at age 25 -- will turn to $1.1 million within 40 years, assuming an annual return of 8%. That comes to socking away about $333 per month, something many families can achieve. And to help you along, Bruno provides some basic strategies and checklists for improved budgeting.

If your employer matches contributions to a 401(k) plan, that's free money -- as long as you stay with the company for a while and get vested. More importantly, you can help to build some discipline by setting up automatic investments from your paycheck.

Keep it simple
True, retirement planning can get confusing -- just do a quick Google search on the topic. Yet Bruno provides an easy-to-understand framework to understand the options, such as IRAs, Roth vehicles, and so on. He looks at some of the tax intricacies and useful strategies.

He also talks about the prickly issues of 401(k) loans, rollovers, withdrawals, and even ways to use various retirement accounts to finance college expenses and the purchase of your first home. In other words, even though Bruno focuses on readers in their 20s and 30s, his advice is applicable to those who are older.

Show me the money
So how can you invest your retirement dollars? Bruno covers basic investment concepts such as diversification and the adverse impact of fees. But he realizes that a do-it-yourself approach can be intimidating. Consider that the typical 401(k) plan has 19 mutual fund options. As a result, Bruno discusses ways to find and work with a financial advisor.

Interestingly enough, some employers offer so-called "managed account" programs. "Think of a managed account as basically being a shortcut to a financial advisor who doesn't just provide you with advice -- they will actually manage your 401(k) portfolio for you," Bruno writes.

Bruno makes an important point that none of us can forget: "No one will take care of your retirement except you." That's kind of scary -- until you think about how much scarier it would be to ignore that advice. As we live longer, and expenses for things such as health care continue to increase, it's critical that we think about retirement. And the good news is that Bruno has a straightforward strategy to help out.

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This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.