Before you reallocate your assets
Be sure to understand the tax consequences of selling investments held outside of a tax-deferred plan (like a Roth, traditional, SEP-, or SIMPLE IRA or a 401(k) or 403(b) employer plan). For instance, you may not want to sell an investment that has increased significantly in value to buy another investment with a similar objective—this wouldn't do much to alter your portfolio's risk level, and you'd be liable for the taxes on the capital gains realized from the sale.
Also, if you're in a high tax bracket and hold assets outside of a tax-deferred plan, consider substituting tax-exempt municipal bond funds for the bond portion of your allocation.
Find out if tax-exempt funds are right for you
Find out if you'd be charged any fees for selling an existing investment.
If you decide to change your asset allocation, determine how much you want to shift at once. If you're planning to move more than 10% of your portfolio, make the shift gradually, perhaps over the next few months or years.