Save as much as you can and sit on it for as long as possible. Such is the modus operandi of investing. But that advice isn't acceptable when it comes to money you plan to spend before your blowout retirement bash.

By process of elimination, you can rule out the following investments for your short-term cash:

  • Retirement accounts
  • Collectibles
  • Long-term bonds
  • Your family
  • The stock market

That's a long list of things to avoid. (Here's more about why each is inappropriate.) So exactly where should your dough go? Your tolerance for risk and your time horizon are the two main factors when deciding where to park your dough. Here are some general guidelines:

For expenses less than five years away: Tax bills, college for your high-school kids, house down payments, rhinoplasty -- often these are events that hover on the near-term time horizon. For short-term goals, stay out of volatile investments such as stocks, and even long-term bonds. Stick with money market accounts, certificates of deposit, Treasury notes, and short-term bonds. (Here's more on the investing tools at your disposal.) We know these vehicles are far from sexy. Still, better safe than sorry.

For expenses between five and 10 years away: Maybe your kids are still in diapers. Or perhaps your dream of a vacation home is still a faint fantasy. Depending on how comfortable you are with investments in the stock market, you might consider putting some of your money in equities. However, as you move closer to your goal, more of your money should be shifted to safer investments.

For expenses more than 10 years away: Retirement. Retirement. Um, retirement. If this blissful state of voluntary unemployment is a decade or more away, you can probably weather the stock market's fickleness with a lot of your dough. The only thing worse than sleeping on cash (or cash equivalents) is waking up at age 65 and realizing that your money is worth less than it was when you were still punching the time clock. The longer your time horizon, the more you mitigate the risks of being in stocks. And history shows that over most 10-year periods, the stock market has been the best place to be. Again, though, as you approach the time you need the money, move toward safer havens.

The key is to make sure you've got what you need when you need it so you don't have to borrow from your future self by dipping into retirement savings or the kids' college fund to pay for the present. Here are some more in-depth money ideas at your fingertips.

Short-term: Find out how to get the most bang for your buck in our Short-Term Savings Center. Compare the rates offered by our partner in savings, MBNA.

Mid-term: Big expenses mean big planning headaches. Don't reach for the Advil. Instead, get informed. Find out the ins and outs of mortgages, college costs, car buying, and retirement planning. If you're already off the clock, consider income-bearing investments like the ones Mathew Emmert pores over in his monthly Income Investor newsletter.

The nebulous future: The goal for a long-term investing horizon is to outrun inflation (at the very least) and make sure you can handle the skyrocketing costs of aging. There's a lot that can go wrong before you set sail on that Royal Caribbean (NYSE:RCL) cruise. (Here are nine retirement killers, for example). But there are a lot of ways to set yourself up right, too. Don't get stymied by a lack of investment ideas or get overwhelmed by the sheer number of mutual funds vying for your retirement dollars. A little homework and a lot of patience will pay off big time with your long-term dollars.

Looking for details on any of these topics, whether it's asset allocation, keeping the most money for yourself (and not Uncle Sam), and safe withdrawal rates? Give Rule Your Retirement a 30-day free trial and receive our "8 Ways to Supercharge Your Retirement" special report.

Dayana Yochim does not own any of the companies mentioned in this article. The Motley Fool is investors writing for investors.