(FORTUNE Magazine) – Picking the right fund may be the main event in your quest for the perfect 401(k), but there are other considerations. Getting great returns without working out the tax implications is like wearing a pair of scruffy old sneakers with a Karl Lagerfeld gown. In other words, it's all in the details.

Sometimes that means thinking outside the 401(k) box. If your company matches what you contribute to your tax-deferred savings, you definitely want to put in as much as it will meet. But you may also want to consider other types of savings. Jonathan Guyton, a national board member of the Financial Planning Association, advises people to put their 401(k) money into bonds--which are taxed at the same rate in any kind of account--but to invest in stocks as much as possible in after-tax accounts. The thing is, when you put pretax money into a 401(k), you save money now, but you'll still be taxed at the other end. For example, if you're in a 15% tax bracket today, but sock away enough to be in a 27% bracket at retirement, you might be paying more taxes down the road than you think.

Savers who are eligible should also investigate a Roth IRA. "The biggest mistake I see people make is neglecting to consider the benefits of the Roth," says Marc Freedman, another FPA board member. You can't put pretax money in a Roth, and your contributions aren't tax-deductible, but the capital gains and withdrawals are tax-free. You can put up to $3,000 a year in a Roth ($3,500 if you're over 50), but only if your adjusted gross income is less than $150,000 for a married couple or $95,000 if you're single.

Don't forget that a regular brokerage account has tax advantages too. Any capital gains on your 401(k) stocks will be taxed as ordinary income when you withdraw, and that could come to more than 30% if you make six figures. If you sell stock from your brokerage account, however, the money will be taxed at the capital gains rate of 20%. Moreover, there's no tax advantage to swapping underperformers for better funds within your 401(k), but in a brokerage account you can use your losses to cancel out this year's capital gains from, say, selling your home. You can write off losses of up to $3,000 more than your capital gains. If you have greater losses than that--which you probably do--you can roll them over indefinitely, year after year. "They're like vacation days," says Guyton. So take your losses now and save them up for when the market recovers. Soon, we hope. --Noshua Watson