Sure they walk around looking for rising damp and knocking on the odd wall to see whether it's hollow, but in house terms this is like kicking the tyres of a second hand car so the salesman won't think you are an idiot. A properly marketed house is capable of getting the heart pumping overtime and turning brain to mush before the potential buyer reaches the front door. Your house may need a good overall paint job, but if the gate and the fence are freshly painted and the front door has been done in a designer colour with a brass lion with a ring in its mouth for a knocker, you've already told the potential new owner that he or she is dealing with the sort of house that will make them look good. If the front garden is a bit of a mess, plant a few flowering shrubs which you can buy at the markets a week or so before the first inspection. If you have a pathway to the front door then buy or hire a dozen standard roses in bloom and bury them in the ground, tub and all, to suggest that they're the work of a caring owner with old fashioned home values.
Standard roses can add tens of thousands to the end price.
Don't forget to mow the lawn on the week before the inspection so that it looks green and inviting by inspection day. Always clean the windows. Clean windows are the sort of thing people don't see, they feel. And on a sunny Saturday morning, clean windows can give the interior of the house a crisp spring look. If there is a down gutter or two showing on the front of the house that has rusted through, replace it - preferably with a copper one.