Look at some of the abandoned buildings in the wilderness, many of them give good examples of how to build and what is considered a good foundation. It may even be worth your while to place a workbench in an abandoned building, and slowly destroy it from the roof down. You will notice that even many wood buildings have foundations for their floorboards, like large 45 degree beams sunk into the ground, with just a few inches above ground that comes into contact with the wooden floor and corner walls.