You should be comparing your subject property to comparable properties that have sold recently in the immediate area. Comparable in terms of square footage, beds/baths, lot size, style, etc. Closer the better. Those recent sales indicate what the market is willing to pay for a home similar to your subject.
What Brad says and look at the condition of the comparable house and upgrades. Such things as granite countertops, updated kitchens, etc. a good appraiser should take those upgrades into consideration. The good appraisers will, but the lazy ones may not. My comments are under the assumption that these upgrades would not be considered over renovated for the area.