Remove excess furniture to create the idea of space. You don't want buyers' zig-zagging ... around or getting tangled up in the clutter of the house.
If walls are dirty a lick of paint costs very little to freshen them up. Clean, plain walls provide buyers with a blank canvas.
If carpets have become tired, discolored and have acquired a few stains over the years, if funds are on hand it can be worthwhile to take them up and throw them out. Depending on the budget and man hours available you could sand & varnish the floorboards underneath. Wooden floors can add to the decor of the room and it gives buyers the option of keeping your new floor or choosing their own carpet!
And finally remove a good chunk of your family photos and ornaments. Although don't go over board and hide all your family possessions as the house will look cold and bare!