They do research based on your property as to size, number of bedrooms, number of bathrooms, year built, lot size, and square footage. They gather data of recent sales in your neighborhood. The appraiser has to locate three similar sized homes which (here is the key) have sold in the neighborhood within one mile of your home within the past six months. The homes that meet the criteria are considered the comparable properties or "comps" for short. The appraiser then takes photos of your street, the front of your home, and rear of your home - as well as interior photos of the living area, kitchen, and main bathroom. He/She will walk through your home to draw a floor plan. The "comps" will have exterior photos only - which the appraiser photographs. The appraiser then chooses the "comps" that most reflect your home making adjustments of monetary value for any differences. He/She uses these figures to come up with the value of your home. So what have we learned? If you want to improve the perceived value of your home - improve your curb appeal. The appraiser takes photos of your street and front of your property to give the lender an idea as to the type of neighborhood in which the home is located. The front gives the lender an idea of its condition and its curb appeal. The back of the home and rear yard is taken because many homeowners don't take care of the rear portion of their homes and backyards. In most cases (over 90% of the time) what you see in the condition of the exterior of a home will be repeated almost exactly in the interior. So again - curb appeal. As they say "a picture is worth a thousand words".
oh, and they cab make or kill your deal if the value is not there. You are right curb appeal is the giant key