First, consider your time horizon: How many years are you away from retiring? A 30-year-old, for example, has at least 30-odd years before they leave the workforce, allowing them more time to recover from market swings and other events.
"The more time that you have, then the more risk you're able to take," said Simon Moore, chief investment officer at online investment advisor FutureAdvisor.
To help you determine what percentage of your portfolio should be invested in riskier assets like stocks, one rule of thumb suggests you subtract your age from 120. That means a 30-year-old should invest up to 90% of her portfolio in stocks, while a 50-year-old should opt for up to 70%.
The remainder of the portfolio should be invested in more conservative plays like bonds and money market funds.
Next: Diversify. Make sure both your stock and bond investments are spread among a variety of asset types and classes.
For stocks, that means investing in both international and U.S. markets, including a mix of large, mid-sized and smaller company stocks. Index funds, which mirror overall market movements, can also help diversify your portfolio.
Vanguard, for example, recommends investing between 20% and 40% of your stock allocation in international markets, and the rest in a mix of U.S. stocks.
Once you have those foundations down, it's time to consider your risk tolerance.
Find out what your stomach for risk is by taking our quiz, then read about the best allocation strategy for you.
If you like to play it safe: Even if you're close to retirement age or just a conservative investor at heart, there is such a thing as playing it too safe.
Even the most conservative retirees should keep at least 20% of their portfolio in stocks, said Maria Bruno, a senior analyst at Vanguard. Otherwise, your portfolio may shrink too quickly when you start withdrawing funds.
Investors in T. Rowe Price's target date retirement funds, for example, have at least 42% of their money allocated to stocks at the time of retirement.
Meanwhile, if you're still several decades away from retirement, you should invest the majority of your portfolio in stocks, no matter how conservative you are. Otherwise, you can run into another threat — the inability to keep up with inflation.
"Cash can be as risky as equities," Bruno said.
If you crave balance: For a balanced portfolio, diversification is the name of the game.
That means not being overly exposed to any one type of investment, sector or region so you can better stomach market volatility.
Take the 2008 stock market crash: People on the verge of retirement who had a chunk of their investments in bonds lost far less of their savings than those who were overly invested in stocks.
Overwhelmed by all of the options? Consider a target date fund, which invests in a mix of stocks, bonds and cash based on an age-appropriate level of risk. If you'd rather go it alone, you can take a look at different provider's target date options and use their investment mix as a guideline.
If you're a risk taker: Just because you have a cast iron stomach when it comes to market volatility doesn't mean you should gamble your retirement savings.
Investing too much of your portfolio in a single sector or, worse, a single stock, is never a good idea.
If you want to live on the edge, you can invest a bigger chunk of your assets in riskier sectors that also provide the opportunity for higher returns, such as emerging markets, said Jeanne Thompson, a vice president at Fidelity Investments.
For investors looking beyond traditional 401(k) investments, FutureAdvisor recommends investing a small portion of your portfolio in real-estate investment trusts, or REITS, which they say tend to offer a relatively solid return over time and protection against inflation.
Lawyers, oil and gas workers and airline employees have some of the best 401(k) plans in the country, typically boasting generous employer matches, high participation rates and low fees, according to a BrightScope report that analyzed some 3,500 company 401(k) plans with at least $100 million in assets.
Employees at many tech firms and utilities fare pretty well too, the report found.
The average balance for participants in Saudi Arabian Oil Company's 401(k) plan, for example, is $490,000 -- nearly 30 times Wal-Mart's ( average balance of $18,000. )
Wal-Mart said more than a million of its workers take part in its plan, including some part-time associates. The company said it matches employee contributions dollar-for-dollar up to 6% of its workers salaries.
Yet, since many of Wal-Mart's workers earn low hourly wages, they may not be able to afford to contribute much.
BrightScope's analysis looked at 2012 data and took into account hundreds of factors, including fees and participation rates, investment options and the level of employer and employee contributions. The higher the score, the more likely savers are to accumulate large enough nest eggs to live their retirement "in dignity," said Brooks Herman, head of data and research at BrightScope.
Southwest Airlines (' plan for pilots was one of the very top performers. It carries some of the lowest fees around, offers plenty of investment options and a generous employer contribution. As a result, participants have saved an average of $350,000. )
The best performing plans also typically offer generous employer contributions, whether it's a traditional match or profit-sharing, something that is especially common in the legal sector.
Workers also tend to earn higher salaries, which allow them to sock away more of their own pay each year.
"These are going to be people who often have advanced degrees, and they are going to understand the importance of 401(k) savings," Herman said.
The retail and hospitality industries, on the other hand, offer some of the country's worst 401(k) plans, BrightScope found.
Workers in these sectors tend to earn lower wages and have higher turnover, making it harder to save. And many workers don't choose to participate at all, BrightScope found.
Here are three reasons why many quake-prone Californians shun insurance:
1) Quake damage rarely exceeds deductibles.
Some argue the insurance is not worth the money for homeowners. Earthquake insurance generally comes with a deductible of 15% of the home's value, according to John Rundle, a professor of physics at the University of California, Davis.
"Most homeowners will never exceed the deductible even if they do get damage," he said.
Most policies are purchased from the California Earthquake Authority, a privately funded, publicly managed organization that was created by the state legislature after severe losses in the Northridge quake threatened to send private insurers packing.
Glenn Pomeroy, CEO of CEA, said he would love to have a zero deductible, but that would make the premiums unaffordable for homeowners. Check out what you would pay on the CEA calculator.
The big deductibles mean money that would have gone to paying insurance premiums might be better spent being invested in temblor resistant home retrofits, according to Rundle. Homeowners could get their houses bolted to bedrock, for example, or braced and reinforced to prevent them from shaking apart.
2) Californians were slammed by the housing bust.
Many Californians were hurt by the real estate crisis and have little or no home equity -- or are underwater on their mortgages.
Jason Simpson, a computer programmer in Sherman Oaks, Calif., outside Los Angeles, bought his $690,000 home with a 3% down mortgage in 2008. The housing bust pushed him underwater -- he soon owed more on his loan than his home was worth.
"With no equity, there was no reason to drop $1,200 a year," he said.
If the big one had hit, he would have simply walked away from his mortgage. Now, however, as home prices have rebounded and he has added on to the house, he's preparing to buy insurance.
3) Mistrust of the California Earthquake Authority's support.
Another factor discouraging homeowners from buying coverage is that the CEA would stop paying claims if catastrophic earthquake losses exceed the the Authority's reserves.
Pomeroy said that homeowners shouldn't worry. Even though, just like any insurer, CEA would stop paying claims once its ability to pay was exceeded, it won't happen. CEA is very well capitalized, he said.
"We could handle two Northridges," he said, about the costliest earthquake in U.S. history.