Topping/Shearing Trees/Shrubs, and Crepe-Murder
Shearing results in a dense tangle of twigs at the surface of a shrub, which shades out any regenerative growth needed for a natural form that could be maintained at a specific size rather than incrementally increasing in size as is the case if sheared. This results in a problem when a shrub becomes overgrown.
Cutting crepe myrtles back to the same height every year, thus destroying the natural form. This is commonly called crepe-murder, and it results from fallacies due to the linkage having myriads of repetitions people now erroneously believe that crepe myrtles must be done that way. A better way would be cutting only a third of the branches each year so that the retention of an aesthetic form and the renewal necessary for abundant blooms are both achieve.
Deforested/Denuded
Buying a wooded lot then cutting all of the trees on it when an adjacent cleared lot could have been purchased instead.
Removing all trees and rocks before leveling a mountainside lot with “topsoil” from cotton field, where it was eroded away over a hundred years ago leaving only the red clay subsoil, and then planting grass and several large caliper trees in rows rather than just starting with a flat cotton field lot.
Erosion
Building a pond with a spillway capacity less than that of the original stream, resulting in just normal rainfall washing away the dam.
Unnecessary Overkill
Fertilizer used on brown grass and bare areas will just be washed away by rain and end up in lakes helping grow aquatic weeds instead.