Which assets should I place inside my IRA or 401k?

"… stash high-income-producing securities, such as high-yield bonds and dividend-paying stocks (especially those that produce nonqualified dividends, such as REITs) within the IRA wrapper, while saving more tax-efficient assets, such as broad market equity index funds, in your taxable account."

Also, you can withdraw contributions from a Roth IRA without penalty, but not earnings. And if you rolled over a traditional IRA into a Roth IRA, you have to wait 5 years before you can withdraw the contributed amount without penalty.

This excellent article from Morningstar lists these and six other common IRA mistakes.