Your home is likely your most valuable investment. But it's hard to know how much it's really worth without selling it.Your tax assessment might give you some idea of your home's value, but the assessment is updated only every few years. What's more, California and other states put a limit on your assessment at a certain percentage increase per year, which means in a booming market your home could be worth much more than its assessed value. In today's market, however, an assessment from a few years ago may be tens of thousands of dollars higher than the actual market value. Getting an accurate sense of a home's value can be critical in certain situations: during a divorce, when settling an estate and when making retirement plans that rely on the equity tied up in your home. (Of course, it's also essential when you're actually buying or selling your house, but in that case the lender will hire the appraiser.) Here's what you need to know to find a reliable appraiser.